Going to try race tires (R888); any pointers?
02-19-2008, 12:31 AM
#16
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Thread Starter
I'd like to say that r compounds like the Toyos will be more sensitive to tire pressures, but the fact is that street tires are pretty sensitive to small pressure changes, too. Most drivers simply don't notice the changes. A lot of people run the RA1 at significantly lower pressures than Toyo suggests, especially with lighter Porsches. The R888 will probably be similar, this way, but I haven't seen enough data on the new version yet to say. I run RA1s in the 27 pound range hot on my 2500-pound car. I think Toyo suggests high 30s or 40.
Keep an eye on the way they're wearing. You might need to unmount the tires halfway through their lifespan and switch left tires with right to even out the wear on the outside shoulders, even with your camber. Better still, get or borrow a probe-type pyrometer and spend a day playing with suspension settings and pressures to work out what's best for your car.
Keep an eye on the way they're wearing. You might need to unmount the tires halfway through their lifespan and switch left tires with right to even out the wear on the outside shoulders, even with your camber. Better still, get or borrow a probe-type pyrometer and spend a day playing with suspension settings and pressures to work out what's best for your car.
And, yes, you're right; I need to get a pyrometer and figure out the optimum pressures with the R888s on my car and my suspension setup. You can always take guesses by the way they "feel", and use chalk marks to detect rollover, but I want to be much more precise than that.
02-19-2008, 12:34 AM
#17
Racer
Thread Starter
He meant that the street tires' lack of grip (relatively speaking) meant you weren't working the brakes as hard as you will with Toyos. He's talking about cooking your brakes -- the sudden (or gradual) fade that comes from the fluid boiling and gasses being released into the hydraulic lines. It can cause anything from a spongy brake pedal to a sudden loss of all brakes.
As you move to grippier tires, you have to find ways to shed heat from your brakes. If you're lucky, it means adding cooling ducts. If the problem is worse, it can be the reason you go to larger calipers and rotors.
As you move to grippier tires, you have to find ways to shed heat from your brakes. If you're lucky, it means adding cooling ducts. If the problem is worse, it can be the reason you go to larger calipers and rotors.
I currently run Ate Super Blue, but I'm going to flush my brakes next week before my next event; maybe I should try Motul.
02-19-2008, 12:37 AM
#18
Racer
Thread Starter
I will. I appreciate all of the feedback, and I have read it all carefully. This is why I love Rennlist!
(not only for the great advice, but even though I don't own a Porsche (yet!), I still feel welcome...)
(actually, I looked at a used Boxster (986) yesterday... maybe it's time...)
(not only for the great advice, but even though I don't own a Porsche (yet!), I still feel welcome...)
(actually, I looked at a used Boxster (986) yesterday... maybe it's time...)
02-19-2008, 12:43 AM
#19
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And, yes, you're right; I need to get a pyrometer and figure out the optimum pressures with the R888s on my car and my suspension setup. You can always take guesses by the way they "feel", and use chalk marks to detect rollover, but I want to be much more precise than that.
02-19-2008, 12:47 AM
#20
Racer
Thread Starter
A pyro won't tell you a lot about pressures on a modern, stiff sidewalled race tire (unless you are heavily under or over inflated). A pyro will tell you about alignment. The goal is usually to get your pressures to the manufacturer's recommendation for your car's weight and then use the pyro and camber to get the temps spread evenly across the tire, with the inside edge being 10-20 degrees warmer than the outside.
So, I guess I was still on the "crude end" of using pyro measurements.
That's yet another thing I look forward to learning and experimenting with...
02-19-2008, 12:09 PM
#21
Rennlist Member
Nah, you are not going to notice 1psi, but you will want to be in a range of generally about 34 to 38hot. as was mentioned the pyrometer is a good way to see if you are getting heat in the tire, and if alignment is working.
in Nascar, tire pressures are a way to change the total spring rates of the suspension system. 1psi on a nascar tire is supposed to have the effect of 50lbs spring change. However, that is nascar sized large sidewall tires. with 30 and 40 aspect ratios, the effect of 1psi would be a lot less.
Mk
in Nascar, tire pressures are a way to change the total spring rates of the suspension system. 1psi on a nascar tire is supposed to have the effect of 50lbs spring change. However, that is nascar sized large sidewall tires. with 30 and 40 aspect ratios, the effect of 1psi would be a lot less.
Mk
Yep, I can notice tire pressure differences of about 1 psi, especially in the RE01R, because they seem (to me) to have a small window where they stick and where they get greasy (too much pressure) or overheat (too little pressure). For my setup, for my car (E36 M3), they seem to like 38psi hot front and rear.
And, yes, you're right; I need to get a pyrometer and figure out the optimum pressures with the R888s on my car and my suspension setup. You can always take guesses by the way they "feel", and use chalk marks to detect rollover, but I want to be much more precise than that.
And, yes, you're right; I need to get a pyrometer and figure out the optimum pressures with the R888s on my car and my suspension setup. You can always take guesses by the way they "feel", and use chalk marks to detect rollover, but I want to be much more precise than that.
Last edited by mark kibort; 02-19-2008 at 01:58 PM.
02-19-2008, 03:08 PM
#22
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I have really enjoyed my RA1s, although I enjoy the Hoosiers even more (except when I have to replace them).
Are you driving to/from track on them? I assume that the R888 is similiar to the RA1. If not driving them on the street, you should look into buying them shaved. They will actually last longer.
Have fun and let us know how you like them.
Buy the Boxster; you deserve it.
Are you driving to/from track on them? I assume that the R888 is similiar to the RA1. If not driving them on the street, you should look into buying them shaved. They will actually last longer.
Have fun and let us know how you like them.
Buy the Boxster; you deserve it.
02-19-2008, 03:18 PM
#23
Racer
Thread Starter
I have really enjoyed my RA1s, although I enjoy the Hoosiers even more (except when I have to replace them).
Are you driving to/from track on them? I assume that the R888 is similiar to the RA1. If not driving them on the street, you should look into buying them shaved. They will actually last longer.
Have fun and let us know how you like them.
Are you driving to/from track on them? I assume that the R888 is similiar to the RA1. If not driving them on the street, you should look into buying them shaved. They will actually last longer.
Have fun and let us know how you like them.
I already ordered them unshaved.
Well, I actually might have, but the color combination just wasn't my first choice. And, since I'm not seriously looking, I can afford to be picky about color.
02-19-2008, 03:32 PM
#24
Race Car
Speaking to the RA1s, at least, it's fine to drive them on the street. Wear isn't your concern with r compounds, heat cycling is. If the R888 is in the same ballpark as the RA1, heat-cycle-resistance-wise, then you won't need to worry about driving to the track on them. A heat-cycle-sensitive tire like the Hoosier is a different case -- you would never want to drive it on the street if you can help it; every heat cycle cuts into the tire's already-short lifespan.
I don't know what the tread depth of the R888 is. For dry use, RA1s were better shaved (although it wasn't absolutely essential). But the Nitto NT01 uses the same rubber as the RA1 and doesn't need to be shaved at all because its tread isn't as deep to start with.
I don't know what the tread depth of the R888 is. For dry use, RA1s were better shaved (although it wasn't absolutely essential). But the Nitto NT01 uses the same rubber as the RA1 and doesn't need to be shaved at all because its tread isn't as deep to start with.
02-19-2008, 03:35 PM
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Hold out for the right color and equipment; there must be a ton of them for sale.
If you don't have to drive too far to the track, go ahead and drive them; just be real careful if it rains, snows (in Houston?), or the street is really cold (it just doesn't do to hit a guardrail on the way to the track). Even so, they aren't bad in the cold (not like MPSCups, which I think are miserable in the cold on a lighter car).
The Toyos always wore out before they heatcycled out.
I have instructed in Boxsters and they are a lot of fun. I thought about buying an S and stripping out the weight, but really like the car I have now.
Have fun!
If you don't have to drive too far to the track, go ahead and drive them; just be real careful if it rains, snows (in Houston?), or the street is really cold (it just doesn't do to hit a guardrail on the way to the track). Even so, they aren't bad in the cold (not like MPSCups, which I think are miserable in the cold on a lighter car).
The Toyos always wore out before they heatcycled out.
I have instructed in Boxsters and they are a lot of fun. I thought about buying an S and stripping out the weight, but really like the car I have now.
Have fun!
02-19-2008, 03:48 PM
#26
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Thread Starter
If I actually buy a Boxster, it will be my daily driver, replacing my S2000. I've already invested way too much in my track car, the M3, to replace it at this point. Plus, the M3 is tons of fun on the track.
02-19-2008, 04:13 PM
#27
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Good thread, and good timing. I'm considering the RA1, and hoping to drive to the track on them. Worst case, I can fit the entire set in my car. Can you believe that?!?! I don't see your name on the DE roster. Are you planning to go to the club race/DE? We will have 2.5 hours track time on Friday, plus the regular runs on Sat/Sun. You should sign up!
02-19-2008, 05:40 PM
#28
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Ive been driving on them to the track for years. sometimes as far as 5 hours!!
ironically, the tires i drive to the track on , i usually only use for practice and sometimes qualify, but lately, ive run as fast or faster times on those, than the "A" set i bring with me. worst case, the times are never more than .5 second off! thats even with tires that are just about to cord!
MK
ironically, the tires i drive to the track on , i usually only use for practice and sometimes qualify, but lately, ive run as fast or faster times on those, than the "A" set i bring with me
. worst case, the times are never more than .5 second off! thats even with tires that are just about to cord!MK
02-19-2008, 06:50 PM
#29
Racer
Thread Starter
Good thread, and good timing. I'm considering the RA1, and hoping to drive to the track on them. Worst case, I can fit the entire set in my car. Can you believe that?!?! I don't see your name on the DE roster. Are you planning to go to the club race/DE? We will have 2.5 hours track time on Friday, plus the regular runs on Sat/Sun. You should sign up!
I registered for the full 3 days. I'm not going to drive up until Friday morning, so someone save me a good pit space out in the weeds!
02-19-2008, 07:21 PM
#30
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Excellent! The DE folks are getting A LOT of track time for the money. And the racers are always an interesting crowd to hang out with. It's gonna be a blast!!
