944spec R888 Tire Review - First 3 Heat Cycles
09-24-2008, 10:35 AM
#16
Three Wheelin'
46 psi sounds way high for anything other than a truck tire. Have you tried running at the lower pressure and changing camber settings. At lower pressure it sounds as though either the tire is rolling over onto the shoulder, or the shoulder is getting pulled into contact with the track by deformation. Considering your lap times were slower its safe to assume that the tire is not rolling onto the shoulder and this issue is caused by the characteristics of the tire to deform under load. Do you have the ability to change camber much from where its currently at? It looks and sounds as though a bit more negative camber may help. You might find that the lower pressure and increased camber to solve the "triangle" problem without much sacrifice to the overall wear.
09-24-2008, 11:33 AM
#17
Three Wheelin'
Keep the data coming Joe! I nearly bought a set of R888s last night and I'm really glad I didn't. If they're only good for 30ish HCs, then I'm going to have to double my tire budget for next year.
09-24-2008, 11:58 AM
#18
Race Director
Thread Starter
Well Couple additional Points.
1) Heat Cycles. I have been getting 26-30 from RA-1 on my last 3-4 sets. I don't expect to get more than this from R888. I know some of you may be targeting more, but my numbers won't get there. I used to get 35+ from RA-1's, but from simply driving harder I get less before the cycle out. The good news is that since I have 6 years of RA-1 cycle data I can compare the R888 to my RA-1 use and come up with life comparison. Your life may vary.
2) Camber... I run -3.5 front and -2.5 rear. This is quite a bit of camber and with the RA-1's would tend to wear the inside down abit more than the outsides. However as I would rotate the tires all around the car this minor extra inside wear would even out over the life span of the tire. In the end there would be no down spots and the tire would cycle out before cording unless driver error caused a flat spot. I am hesitant in trying to get more camber as everyone says LESS camber. Also while I can get more camber in front the rear is going to be tough and changing the camber split front to rear may throw the entire car's balance off. The other issue is that on a weekend I used both RA-1 and R888. So adjusting camber is not that easy. Front is doable with camber plates, but it is not realisting on the rear.
3) Heat Cycling.. I did a proper heat cycle on these tires. I don't know if it helps or not, but was easy to do and in the interest of getting all the life I can it was worth it to try. If I get crappy life you can't say it was because of not heat cycling. I may or may not heat cycle my next set of R888.
4) The really odd thing here is that it seems that guys with lower profile tires with big wheels don't seem to have the same issues we are on the 225/50 with 15x7's. I wonder if the issues is a combination of our taller sidewall and is causing an oddly deformed shape.
Next time out I will get tire temps. Normally this is done in 3 places. I will try to get 5 places and then compare those temps with RA-1's. Temps probably will be taken after the session so overall temp may not be there, but im looking for how the tire's temp changes accros the tire and how that is different on RA-1 vs R888.
These tires are proving to be odd ducks for our cars especially. They may prove to be just fine once we find the sweet spot, but finding that sweet spot seems very challenging. I really hope this is the only thing we are missing althought it seems like while in larger diameters with short sidewalls the tire seems to work ok for our size it is a challenge. Maybe the tire was designed for lower profile tires and a taller profile 15 wheel just does not work? Hard to say really.
1) Heat Cycles. I have been getting 26-30 from RA-1 on my last 3-4 sets. I don't expect to get more than this from R888. I know some of you may be targeting more, but my numbers won't get there. I used to get 35+ from RA-1's, but from simply driving harder I get less before the cycle out. The good news is that since I have 6 years of RA-1 cycle data I can compare the R888 to my RA-1 use and come up with life comparison. Your life may vary.
2) Camber... I run -3.5 front and -2.5 rear. This is quite a bit of camber and with the RA-1's would tend to wear the inside down abit more than the outsides. However as I would rotate the tires all around the car this minor extra inside wear would even out over the life span of the tire. In the end there would be no down spots and the tire would cycle out before cording unless driver error caused a flat spot. I am hesitant in trying to get more camber as everyone says LESS camber. Also while I can get more camber in front the rear is going to be tough and changing the camber split front to rear may throw the entire car's balance off. The other issue is that on a weekend I used both RA-1 and R888. So adjusting camber is not that easy. Front is doable with camber plates, but it is not realisting on the rear.
3) Heat Cycling.. I did a proper heat cycle on these tires. I don't know if it helps or not, but was easy to do and in the interest of getting all the life I can it was worth it to try. If I get crappy life you can't say it was because of not heat cycling. I may or may not heat cycle my next set of R888.
4) The really odd thing here is that it seems that guys with lower profile tires with big wheels don't seem to have the same issues we are on the 225/50 with 15x7's. I wonder if the issues is a combination of our taller sidewall and is causing an oddly deformed shape.
Next time out I will get tire temps. Normally this is done in 3 places. I will try to get 5 places and then compare those temps with RA-1's. Temps probably will be taken after the session so overall temp may not be there, but im looking for how the tire's temp changes accros the tire and how that is different on RA-1 vs R888.
These tires are proving to be odd ducks for our cars especially. They may prove to be just fine once we find the sweet spot, but finding that sweet spot seems very challenging. I really hope this is the only thing we are missing althought it seems like while in larger diameters with short sidewalls the tire seems to work ok for our size it is a challenge. Maybe the tire was designed for lower profile tires and a taller profile 15 wheel just does not work? Hard to say really.
Last edited by M758; 09-24-2008 at 12:13 PM.
09-24-2008, 02:14 PM
#19
Three Wheelin'
I am hesitant in trying to get more camber as everyone says LESS camber. Also while I can get more camber in front the rear is going to be tough and changing the camber split front to rear may throw the entire car's balance off. The other issue is that on a weekend I used both RA-1 and R888. So adjusting camber is not that easy. Front is doable with camber plates, but it is not realisting on the rear.
09-24-2008, 05:03 PM
#20
Race Director
Thread Starter
Here some information I found poking around Spec Miata web forums. Much was centered around a test SCCA did for Spec Miata
Nothing definitive, but more information to put in our caps. I am also probing the Spec-E30 forums to see what I can learn.
In the end, my only concern is that ALL of the drivers at the test gave the R888 the worst feedback of the three as far as driveability etc. Most said the turn in was great due to stiffer sidewalls but the compound wasn't as good as the sidewall construction and mid corner grip and predictability were not as good as the RA1 or the Hoosier. Is the R888 the right choice? I don't know... I think the cars will be harder to drive fast. In a class widely populated by relatively un experienced drivers... I don't think a tire that is hard to drive on is the best choice, but when you throw in all the other factors, it may have been the best decision. The sky isn't falling, we will have to get used to a new tire, but at the end of the day, we should all be fine with the R888.
Jim
--------------------
Jim Drago
East Street Auto Salvage
jdrago1@aol.com
2006-2007 Mid-West Division
Champion
EAST STREET RACING
Jim
--------------------
Jim Drago
East Street Auto Salvage
jdrago1@aol.com
2006-2007 Mid-West Division
Champion
EAST STREET RACING
Based on my experience so far with the R888 on an SM, it is a much more consistent tire than the RA1 - i.e. the laptimes are the same whether it's a new 4/32 shaved tire or a nearly worn out tire. It's fastest about in the middle of that lifespan, and it is only slightly faster at that point. Overall, I'd say it's consistency is similar to that of the Hoosier.
What we do not know yet (haven't had a chance to test yet,) is whether or not it's considerably faster at 2/32 shave. I certainly hope it's not.
--------------------
-Jason Saini :: Fort Worth, TX
-Team MER :: 2006 MX-5 Cup Runner Up
-2007 MX-5 Cup Champion!
What we do not know yet (haven't had a chance to test yet,) is whether or not it's considerably faster at 2/32 shave. I certainly hope it's not.
--------------------
-Jason Saini :: Fort Worth, TX
-Team MER :: 2006 MX-5 Cup Runner Up
-2007 MX-5 Cup Champion!
From the Aim Tire Website...
There are a multitude of questions being asked about the difference between the RA-1 and the new R-888.
Our company was the very first company to sell the RA-1 back in 1992. In fact we were the company that originally tested a prototype RA-1 that allowed TOYO the feedback necessary to commit the RA-1 to the USA market. Thus, we have a bit of experience with the RA-1 tire!
The greatest difference between the RA-1 and the R-888 is the tires construction. The R-888 is of an all new design both in tread and construction.
The most obvious difference being the tread pattern and molded tread depth. The R-888 grooves are molded to 6/32nds of an inch. Whereas the RA-1 grooves are staggard with the inner grooves at 8/32nds of an inch and the outer most grooves at 6/32nds. Additionally the R-888 has less and larger tread blocks to promote a quicker steering response and better mid-corner grip.
It should be noted that shaving a R-888 due to the wider grooves will not ceate a 'slick tire' as in the case of shaving a RA-1 to below 4/32nds. The R-888 when shaved even as low as 2/32nds will not be a virtual slick tire but will continue to have wide rain grooves.
The wider grooves on the R-888 does enhance the wet weather performance of the tire and has proven superior in the wet than the RA-1.
To maximize the performance of the R-888 over the RA-1, especially on Front wheel drive RACE cars and Spec Miata's camber, tire pressure and driving technique must be modified.
The R-888 with the stiffer sidewall and softer undertread construction requires significantly less initial camber settings and higher pressure.
By design the R-888 promotes higher levels of grip under braking and at mid-corner.
So, if you simply switch out a RA-1 for a R-888 don't expect your FWD car to rotate in at mid-corner without taking all of the camber out of the rear suspension settings. Furthermore, less camber in the front will aid turn-in. And an increase in starting and operating pressure of the R-888 over the RA-1, will aid in overall traction and increase tire life.
There are a multitude of questions being asked about the difference between the RA-1 and the new R-888.
Our company was the very first company to sell the RA-1 back in 1992. In fact we were the company that originally tested a prototype RA-1 that allowed TOYO the feedback necessary to commit the RA-1 to the USA market. Thus, we have a bit of experience with the RA-1 tire!
The greatest difference between the RA-1 and the R-888 is the tires construction. The R-888 is of an all new design both in tread and construction.
The most obvious difference being the tread pattern and molded tread depth. The R-888 grooves are molded to 6/32nds of an inch. Whereas the RA-1 grooves are staggard with the inner grooves at 8/32nds of an inch and the outer most grooves at 6/32nds. Additionally the R-888 has less and larger tread blocks to promote a quicker steering response and better mid-corner grip.
It should be noted that shaving a R-888 due to the wider grooves will not ceate a 'slick tire' as in the case of shaving a RA-1 to below 4/32nds. The R-888 when shaved even as low as 2/32nds will not be a virtual slick tire but will continue to have wide rain grooves.
The wider grooves on the R-888 does enhance the wet weather performance of the tire and has proven superior in the wet than the RA-1.
To maximize the performance of the R-888 over the RA-1, especially on Front wheel drive RACE cars and Spec Miata's camber, tire pressure and driving technique must be modified.
The R-888 with the stiffer sidewall and softer undertread construction requires significantly less initial camber settings and higher pressure.
By design the R-888 promotes higher levels of grip under braking and at mid-corner.
So, if you simply switch out a RA-1 for a R-888 don't expect your FWD car to rotate in at mid-corner without taking all of the camber out of the rear suspension settings. Furthermore, less camber in the front will aid turn-in. And an increase in starting and operating pressure of the R-888 over the RA-1, will aid in overall traction and increase tire life.
I received information from Toyo on some of the differences of the RA1 and the R888.
The tire is not a bolt on and away you go replacement.
From Toyo Tire USA
The Toyo Proxes R888 is a totally redesigned product. The construction is completely different than the RA1. Therefore it may require a setup change.
The Proxes R888 is a more refined product that requires less slip angles and less camber than the Proxes RA1. If the R888 is driven with the same setup, tire pressures and driving style it may go slower.The Proxes R888 will not respond well if driven at the same slip angles as the RA1. For example if you slide your car around and build up to much heat the tire will wear prematurely. Toyo Tire USA
With that being said consider this.
High negative camber will give you more bite in the turns but has less contact patch straight ahead, so you have less braking force. With less negative camber braking points can be deeper.
All of the instructors I've talked to say "smooth is fast." Sliding scrubs off speed and overheats the tires. High tire temps should not exceed 200 degrees.
The new tread design of the Proxes R888 is less succeptable to tread squirm so shaving is less of an issue. But shaved tires are lighter so they have less rotating mass. The Proxes R888 has tread grooves full depth, so a 3/32 tire will still have some water channeling.
When I get more information I'll be sure to pass it on.
Joe
TheTireShoppe
The tire is not a bolt on and away you go replacement.
From Toyo Tire USA
The Toyo Proxes R888 is a totally redesigned product. The construction is completely different than the RA1. Therefore it may require a setup change.
The Proxes R888 is a more refined product that requires less slip angles and less camber than the Proxes RA1. If the R888 is driven with the same setup, tire pressures and driving style it may go slower.The Proxes R888 will not respond well if driven at the same slip angles as the RA1. For example if you slide your car around and build up to much heat the tire will wear prematurely. Toyo Tire USA
With that being said consider this.
High negative camber will give you more bite in the turns but has less contact patch straight ahead, so you have less braking force. With less negative camber braking points can be deeper.
All of the instructors I've talked to say "smooth is fast." Sliding scrubs off speed and overheats the tires. High tire temps should not exceed 200 degrees.
The new tread design of the Proxes R888 is less succeptable to tread squirm so shaving is less of an issue. But shaved tires are lighter so they have less rotating mass. The Proxes R888 has tread grooves full depth, so a 3/32 tire will still have some water channeling.
When I get more information I'll be sure to pass it on.
Joe
TheTireShoppe
Nothing definitive, but more information to put in our caps. I am also probing the Spec-E30 forums to see what I can learn.
09-24-2008, 05:31 PM
#21
Race Director
Thread Starter
I have been thinking about this statement along with the feedback from low profile guys.
Here goes my thinking. The tires are shaped like a "U". Wider low profile tires have shorter sidewalls in relation to the tread. a 50 series tire has a side wall that is 50% as tall as the tread width.
So consider what happens with a stiff tread area and soft sidewall.
The tire on left is a taller sidewall with stiff tread and soft sidewalls. It allows the side walls to move sideways, but the stiff tread stays flat. When we ran RA-1 we never suffered rolling over the edge of the tire unless at very minimal camber settings.
The middle tire has stiff sidewall, but softer tread. This allows the tread to buckle in a bit putting more edge load on the sidewalll and pulled in the center of the tire off the road. Adding more air would overround the tire a bit and help support the center of the tread.
A short sidewall tire however puts less load in the tread due to the shorter lever arm allowing less buckling in the middle.
Anyway it is a theory, but probably wrong....
From the Aim Tire Website...
The R-888 with the stiffer sidewall and softer undertread construction requires significantly less initial camber settings and higher pressure.
The R-888 with the stiffer sidewall and softer undertread construction requires significantly less initial camber settings and higher pressure.
Here goes my thinking. The tires are shaped like a "U". Wider low profile tires have shorter sidewalls in relation to the tread. a 50 series tire has a side wall that is 50% as tall as the tread width.
So consider what happens with a stiff tread area and soft sidewall.
The tire on left is a taller sidewall with stiff tread and soft sidewalls. It allows the side walls to move sideways, but the stiff tread stays flat. When we ran RA-1 we never suffered rolling over the edge of the tire unless at very minimal camber settings.
The middle tire has stiff sidewall, but softer tread. This allows the tread to buckle in a bit putting more edge load on the sidewalll and pulled in the center of the tire off the road. Adding more air would overround the tire a bit and help support the center of the tread.
A short sidewall tire however puts less load in the tread due to the shorter lever arm allowing less buckling in the middle.
Anyway it is a theory, but probably wrong....
09-24-2008, 05:32 PM
#22
Three Wheelin'
Sounds like there's an advantage to be had for a year or so until everyone can figure out a new setup. For those that can do it quickly will probably see some nice returns.
09-24-2008, 11:46 PM
#23
Rennlist Member
I have been thinking about this statement along with the feedback from low profile guys.
Here goes my thinking. The tires are shaped like a "U". Wider low profile tires have shorter sidewalls in relation to the tread. a 50 series tire has a side wall that is 50% as tall as the tread width.
So consider what happens with a stiff tread area and soft sidewall.
The tire on left is a taller sidewall with stiff tread and soft sidewalls. It allows the side walls to move sideways, but the stiff tread stays flat. When we ran RA-1 we never suffered rolling over the edge of the tire unless at very minimal camber settings.
The middle tire has stiff sidewall, but softer tread. This allows the tread to buckle in a bit putting more edge load on the sidewalll and pulled in the center of the tire off the road. Adding more air would overround the tire a bit and help support the center of the tread.
A short sidewall tire however puts less load in the tread due to the shorter lever arm allowing less buckling in the middle.
Anyway it is a theory, but probably wrong....
Here goes my thinking. The tires are shaped like a "U". Wider low profile tires have shorter sidewalls in relation to the tread. a 50 series tire has a side wall that is 50% as tall as the tread width.
So consider what happens with a stiff tread area and soft sidewall.
The tire on left is a taller sidewall with stiff tread and soft sidewalls. It allows the side walls to move sideways, but the stiff tread stays flat. When we ran RA-1 we never suffered rolling over the edge of the tire unless at very minimal camber settings.
The middle tire has stiff sidewall, but softer tread. This allows the tread to buckle in a bit putting more edge load on the sidewalll and pulled in the center of the tire off the road. Adding more air would overround the tire a bit and help support the center of the tread.
A short sidewall tire however puts less load in the tread due to the shorter lever arm allowing less buckling in the middle.
Anyway it is a theory, but probably wrong....
09-24-2008, 11:56 PM
#24
Rennlist Member
Joe -
This makes a lot of sense both in explainaing our issues, and explaining why there is so much variation in opinion on these tires. We run about the tallest sidewalls out there, and likely pretty far away from what Toyo spent most of their time developing. So the "coventional wisdom" even from Toyo, may not apply here.
So I guess we'll be moving to the 225/45/15 R-888?
I have driven a friends Spec 944 on that size R-888 (it was all the trackside vendor had in a full tread, and it was pouring out for the enduro). It does shorten the gearing a bit.
This makes a lot of sense both in explainaing our issues, and explaining why there is so much variation in opinion on these tires. We run about the tallest sidewalls out there, and likely pretty far away from what Toyo spent most of their time developing. So the "coventional wisdom" even from Toyo, may not apply here.
So I guess we'll be moving to the 225/45/15 R-888?
I have driven a friends Spec 944 on that size R-888 (it was all the trackside vendor had in a full tread, and it was pouring out for the enduro). It does shorten the gearing a bit.
09-25-2008, 04:03 AM
#25
Nordschleife Master
I have around 15 heat cycles on a set of 888's and have found them to be a good tire. At this point I cannot do a direct comparison with the RA1 due to the fact that I'm running the 235/50-15's in the 888 and always ran the 225/45-15 for the RA1. I can tell you that my lap times are faster on the 888's, but that is likely due to the greater width of the 235's.
Like Joe, I'm running -3.5 front/-2.25 rear camber (2,500lb with driver). With this set up it appears that the insides are not wearing as quickly on the 888's as it did on the RA1's. I am not having a problem with rolling the outside edge and I'm running 35 hot with tire temps of around 190 in the hot pits.
I originally ran the tire on 15x8's rims which worked well. I then needed those rims for some Hoosiers and put the 888's on 15x7 cookies. The 235's definately felt better on the 8" rims but my times are still faster than running the 225 RA1's on 7" rims.
Like Joe, I'm running -3.5 front/-2.25 rear camber (2,500lb with driver). With this set up it appears that the insides are not wearing as quickly on the 888's as it did on the RA1's. I am not having a problem with rolling the outside edge and I'm running 35 hot with tire temps of around 190 in the hot pits.
I originally ran the tire on 15x8's rims which worked well. I then needed those rims for some Hoosiers and put the 888's on 15x7 cookies. The 235's definately felt better on the 8" rims but my times are still faster than running the 225 RA1's on 7" rims.
09-25-2008, 10:55 AM
#26
Race Director
Thread Starter
Tim,
You bring up and interesting point since we had 924S guy put some 235/50 R15 on his 924S Spec car. Also on 15x7's. It was a very tight fit for 235's, but he did not seem to roll the 235's the way he did the 225's.
I guess we could change tire size to a 225/45 or 235/50, but it still seems so strange that we are having issues with a 225/50. Could it be something unique about the 225/50? I would not expect to be vastly different from a 205/50, 225/45 or 235/50 all in 15inch sizes.
You bring up and interesting point since we had 924S guy put some 235/50 R15 on his 924S Spec car. Also on 15x7's. It was a very tight fit for 235's, but he did not seem to roll the 235's the way he did the 225's.
I guess we could change tire size to a 225/45 or 235/50, but it still seems so strange that we are having issues with a 225/50. Could it be something unique about the 225/50? I would not expect to be vastly different from a 205/50, 225/45 or 235/50 all in 15inch sizes.
09-25-2008, 02:12 PM
#27
Rennlist Member
Joe, I can't find it now, but I seem to remember reading you didn't take tire temps that first weekend out, correct?
Honestly, I'd treat this first outing purely as an anecdote: it's interesting, to be sure, but there's just too little empirical evidence to really deduce anything worthwhile. Especially without having taken temps, we really can't say much at this point in time. How was the track surface itself that weekend? It could've also been contributing to your slipperiness.
Honestly, I'd treat this first outing purely as an anecdote: it's interesting, to be sure, but there's just too little empirical evidence to really deduce anything worthwhile. Especially without having taken temps, we really can't say much at this point in time. How was the track surface itself that weekend? It could've also been contributing to your slipperiness.
09-25-2008, 03:14 PM
#28
Race Director
Thread Starter
Joe, I can't find it now, but I seem to remember reading you didn't take tire temps that first weekend out, correct?
Honestly, I'd treat this first outing purely as an anecdote: it's interesting, to be sure, but there's just too little empirical evidence to really deduce anything worthwhile. Especially without having taken temps, we really can't say much at this point in time. How was the track surface itself that weekend? It could've also been contributing to your slipperiness.
Honestly, I'd treat this first outing purely as an anecdote: it's interesting, to be sure, but there's just too little empirical evidence to really deduce anything worthwhile. Especially without having taken temps, we really can't say much at this point in time. How was the track surface itself that weekend? It could've also been contributing to your slipperiness.
Now the track was PIR and as always in september it was hot. Having run a september race at PIR for that past 5 years I know what the track does and how it impacts speed and grip.
Now when it comes to tire temps they would help, but lack of them does not invalidate what I have learned. Next time out I will be taking temps in an attempt to learn the distribution of temp across the tread. I will also gather a baseline with RA-1's. Now when it comes to issues like over heating the the rubber I don't think it am doing more than the RA-1. There could be local spots, but overall I drove just as hard at over conditions we have normally experienced. The tires grew from cold to hot pressures by a very similar level as with the RA-1. For RA-1 I would start 31-32 to get 38-39 hot. That is about 6-8 psi increasse from cold. The R888 were also about 6-8 psi increase from cold. So overall the temps are similar. Clearly their could be hot spots on the R888 that are an important factor. I will try to figure this out come our next race.
10-03-2008, 04:20 PM
#30
Race Director
Thread Starter
Some additional data on the R888.
http://spda-online.ca/modules/newbb/...=4306&forum=10
The zip file has some interesting data plots on the R888 vs RA-1.
Lots of technical stuff in there.
http://spda-online.ca/modules/newbb/...=4306&forum=10
The zip file has some interesting data plots on the R888 vs RA-1.
Lots of technical stuff in there.