Looks vs. Performance ...... What do you think?
09-13-2005, 09:33 PM
#61
Burning Brakes
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That "2002wheelman" lists Porsche wheels all the time and nobody ever bids on them. I have seen his ads for over a year now. As Ted says, you can get those same wheels used from a private seller for much less.
09-14-2005, 12:43 AM
#62
Race Car
yea, ernies alloys in florida. they are way overpriced.
09-14-2005, 01:42 AM
#64
Nordschleife Master
Originally Posted by Manning
Remember that statement
Tire weight difference between a 225/50 15 and a 225/50 16 may be as little as half a pound or more than a couple pounds. To use the listed weights for Hoosier Tires R3S04 tires for example, the 225/50 16 is actually 2 pound HEAVIER than the comparable tire for a 15" wheel. And yes that weight will make a difference since it is further out on the rotating mass.
Also, I have heard and read many times racers commenting on how they like the way higher profile tires transition in corners better than lower profile tires, though this may not be so much the case with newer tires. Since this is merely anecdotal I will defer to somebody like Joe for his opinion. But actually, in the case of the 225/50 15 versus 225/50 16 debate, the point is moot, since the aspect ratio (sidewall profile) is the same, on paper at least.
Tire weight difference between a 225/50 15 and a 225/50 16 may be as little as half a pound or more than a couple pounds. To use the listed weights for Hoosier Tires R3S04 tires for example, the 225/50 16 is actually 2 pound HEAVIER than the comparable tire for a 15" wheel. And yes that weight will make a difference since it is further out on the rotating mass.
Also, I have heard and read many times racers commenting on how they like the way higher profile tires transition in corners better than lower profile tires, though this may not be so much the case with newer tires. Since this is merely anecdotal I will defer to somebody like Joe for his opinion. But actually, in the case of the 225/50 15 versus 225/50 16 debate, the point is moot, since the aspect ratio (sidewall profile) is the same, on paper at least.
Manning what I am saying is that a 225/50/ 16 would be more of a 225/60/ 15 if you want to keep same overall size for street driving. I am not sure what the weight of a 225/60/ 15 is compared to a 225/50/ 16 but I bet its more!
Last edited by Fishey; 09-14-2005 at 01:58 AM.
09-14-2005, 01:50 AM
#65
Nordschleife Master
Originally Posted by M758
I said this in post #2 of this thread...
That post is really lacking information...
Tire type?/Sidewall Size of the 15" and 16" Tires/Width of bothe tires/What kind of 15" and 16" rims?/ Tire Pressure?
Hard to prove that 15" rims made the diffrence in time without this information.
09-14-2005, 02:18 AM
#66
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Originally Posted by joseph mitro
yea, ernies alloys in florida....
Its a nice car.
And Fishey... 15" wheels are the bomb diggidy...just accept it.
09-14-2005, 12:17 PM
#67
Rennlist Member
Manning, Fishey,
Original question was referencing a comparison between 225/50/15 Toyo RA1s on 7” PDs, versus 225/40/18 frt and 265/35/18 rear Pirelli P-Zero Corsa’s. The 225-18 Corsa weighs 20 lbs, the 265-18 Corsa weighs 23 lbs, the 225-15 Toyo weighs 23 lbs. So here, the much wider tire is actually the same weight as the narrower tire. However, the weight difference will be in the wheels, where the 10 x 18” 993 Twist will probably be at least 10 lbs heavier than a 7 x 15” PD.
Original question was referencing a comparison between 225/50/15 Toyo RA1s on 7” PDs, versus 225/40/18 frt and 265/35/18 rear Pirelli P-Zero Corsa’s. The 225-18 Corsa weighs 20 lbs, the 265-18 Corsa weighs 23 lbs, the 225-15 Toyo weighs 23 lbs. So here, the much wider tire is actually the same weight as the narrower tire. However, the weight difference will be in the wheels, where the 10 x 18” 993 Twist will probably be at least 10 lbs heavier than a 7 x 15” PD.
09-14-2005, 12:21 PM
#68
Rennlist Member
Originally Posted by Travis - sflraver
The couple of lbs of unsprung weight is not as noticeable in a track situation where you are not looking at uneven road surfaces (street) or hard quick turns(autox). I went on an unsprung weight diet on my autox car and in that application you can notice any reduction with a distinct jump in suspension response time.
I was able to shed over 12 lbs per wheel (front) and it did wanders for the cars handling. Before the "diet" I was running 15" phone dials with 60 series tires. Again, track events where the surface is even and you do not ask the car to respond as dramatically, unsprung weight plays a smaller role. In every day driving and autox you will notice it much more.
I was able to shed over 12 lbs per wheel (front) and it did wanders for the cars handling. Before the "diet" I was running 15" phone dials with 60 series tires. Again, track events where the surface is even and you do not ask the car to respond as dramatically, unsprung weight plays a smaller role. In every day driving and autox you will notice it much more.
Travis,
So you effectively shortened your overall final drive ratio (60 series to 50 series tire), decreased weight (by 12 lbs) and went wider (7” PD – 8” Fuchs)? Im sure there would be a noticeable improvement. My point was never that lighter/shorter/wider doesn’t improve handling and performance, my point is that wider/heavier may be an equal or improved trade off to narrower/lighter (grip versus acceleration).
Also, can I ask, what is your high speed track experience? Im curious about your point that autocross/street driving is more dramatic and requires a more responsive suspension than full track racing. I cant imagine street use being more sensitive to unsprung weight and suspension setups than a road course application.
09-14-2005, 12:28 PM
#69
Race Director
Originally Posted by Fishey
That post is really lacking information...
Tire type?/Sidewall Size of the 15" and 16" Tires/Width of bothe tires/What kind of 15" and 16" rims?/ Tire Pressure?
Hard to prove that 15" rims made the diffrence in time without this information.
Tire type?/Sidewall Size of the 15" and 16" Tires/Width of bothe tires/What kind of 15" and 16" rims?/ Tire Pressure?
Hard to prove that 15" rims made the diffrence in time without this information.
I said both tire were 225/50's one on 16" wheels the other on 15". Both were the same tire type too Kumho Victoracers. Both I assume ran at the same pressure as there would be no reason to change this. They were run with in an hour and 1/2 of each other on the same day with no change in track conditions. The driver was still learning the track, but the second session was on the 16" where he should have been faster, but was not. 15x7 Phone dials and 16x7 Cup 1's were tires used on 2450 lbs 924S. Now for those not familar with Vicotoracers the are as fast right new as in the first 5-6 heat cycles so tire grip was not an issue. Feedback from the driver was that tires stuck really good, but the car seemed slow. This was due to taller gearing mostly. The two second change was noted by comparing hot lap times from the first session on 15's to the second on 16's. In general there was a 2 second change between the laps of the tow sessions. As a control I also was on track in those two seesions my lap times were consistant between the those two seesions so this confrims no large change in track conditions.
That enough data for you?
09-14-2005, 12:29 PM
#70
Rennlist Member
Originally Posted by M758
Don't forget on teh 944 NA if you run 225/50 on 15" wheels rather than 16" you get the advantge of lowering gearing too. I rode in a 944 NA with light 18" wheels a time back. Grip seemed good, but accelration was poor since the diameter was actually larger than stock.
So for such a low hp machine you really want the lower gearing a 225/50 on 15" wheel can provide. The NA car has lots of grip, but no hp so what you need most is acceleration.
Once you move to 951 you have more hp and can get away with a larger tire. You have solid hp with these cars so you gaining a bit more grip is probably more important and a little bit more grip.
Also would seem that if you could get 245 or wider tire in 15" low profile that would be good for a 951. 225's really too small. Since you can't however you are forced in to 16" wheel. Then you lose the advanage of smaller diameter. So in a 951 16 vs 17 vs 18 is more an issues of wheel & tire weight and tire width as diameters tend to be similar.
So for such a low hp machine you really want the lower gearing a 225/50 on 15" wheel can provide. The NA car has lots of grip, but no hp so what you need most is acceleration.
Once you move to 951 you have more hp and can get away with a larger tire. You have solid hp with these cars so you gaining a bit more grip is probably more important and a little bit more grip.
Also would seem that if you could get 245 or wider tire in 15" low profile that would be good for a 951. 225's really too small. Since you can't however you are forced in to 16" wheel. Then you lose the advanage of smaller diameter. So in a 951 16 vs 17 vs 18 is more an issues of wheel & tire weight and tire width as diameters tend to be similar.
Yep, going to a lower profile tire will help acceleration – more so than just reducing unsprung or rotational weight.
In PCA Club Racing, I don’t recall that last time I saw a 944 on 15” wheels. The fastest guys that I know or ever saw in I Class 944s were running 8 and 9 x 16s Fuchs in PCA, but would put on the low profile 15s when they raced SCCA to meet the rules. Im assuming that these guys would have used the 15s in PCA if they thought they were a faster setup.
I DE’d, autocrossed, and Club Raced a 944S (which is really an N/A with more expensive engine parts) for 10 years. It’s a finesse car. Once you get any speed going in the forward direction, you don’t want to give it up for anything, because it takes it awhile to get going again. So as little braking and the highest possible corner speeds are absolutely essential for going fast. I found that the more tire I put under the car, the better, which would allow me to keep the cornering speeds up. But this can be track dependent.
If money was no object and class rules did not interfere, I would have put 10x18s on that car and run 285/30s, which have the same diameter as a 245/45/16, in back (mainly for turn 2 at Brainerd and the kink at Road America) just to try it.
09-14-2005, 12:34 PM
#71
Rennlist Member
In the end, I don’t want to be perceived as arguing with anyone on this. I think that all the points about running the lightest and lowest profile wheel/tire combination are very valid. I just want to illustrate that there can be a benefit to using a wider tire. Unfortunately the wider wheel/tire setups will typically weigh more, so then the decision becomes a compromise or trade off, cornering versus acceleration.
For the street, who cares. Go with what looks the best or gives the best ride quality (both are a personal taste). Shouldn’t be racing anyone on the street hard enough that a few lbs per wheel will make a difference.
For an autocross or track application, regardless of what “feels” better, you will probably have to do some testing and lap time comparisons (which is difficult for an autocross course) to determine what gives a performance advantage.
For the street, who cares. Go with what looks the best or gives the best ride quality (both are a personal taste). Shouldn’t be racing anyone on the street hard enough that a few lbs per wheel will make a difference.
For an autocross or track application, regardless of what “feels” better, you will probably have to do some testing and lap time comparisons (which is difficult for an autocross course) to determine what gives a performance advantage.
09-14-2005, 12:42 PM
#72
Race Director
Originally Posted by Oddjob
Joe,
In PCA Club Racing, I don’t recall that last time I saw a 944 on 15” wheels. The fastest guys that I know or ever saw in I Class 944s were running 8 and 9 x 16s Fuchs in PCA, but would put on the low profile 15s when they raced SCCA to meet the rules. Im assuming that these guys would have used the 15s in PCA if they thought they were a faster setup.
In PCA Club Racing, I don’t recall that last time I saw a 944 on 15” wheels. The fastest guys that I know or ever saw in I Class 944s were running 8 and 9 x 16s Fuchs in PCA, but would put on the low profile 15s when they raced SCCA to meet the rules. Im assuming that these guys would have used the 15s in PCA if they thought they were a faster setup.
SCCA limits you to a max width of 7" which means 225's. 16" wheels are legal in SCCA with a max of 7" wide. So... maybe the issues is with the 225 size.
If you all you can use the 225 width then go with smaller wheel & tire to gain gearing. If you can use a 245 then you forced to at least 16". Maybe the benfits of 245 out weight the gains of the smaller diamter.
Really corning wise a 245/45 will have more grip than a 225/50. Both tire have very close to the same sidewall, but 245 is much wider. The same tire/wheel combo will beheavier in 245/45 16 bs 225/50 15 that is a fact. However extra grip from the 20 mm more section may overcome this. PCA cars can run the wider tire, but SCCA cars cannot due to wheel width rules.
I guess then ideal would be a 245/45 on a 15"x 8 wheel. Too bad that there is no 245 for a 15" wheel.
Also remembe that SCCA cars run ligher than PCA I cars by 200 lbs or so.
SCCA ITS = 2715 WITH driver were as I-stock is 2779 withOUT driver.
09-14-2005, 01:16 PM
#73
Rennlist Member
These guys would pull some big ballast out when running SCCA, so going with a narrower tire on a lighter car, was not as noticeable as going with a narrower tire on the same weight car.
[ Edit (added): and yes, they were running 245/45/16s on the 8s and 9s. ]
And also, my S had to weigh 2822, which is damn heavy. So it benefitted by having a fat tire to help it transition in corners.
Another note, I find that the 16" 245s will go off sooner in longer run sessions/races than the 285s. They start to get greasy and loose several laps sooner that the 285s. More rubber takes longer to heat up, and the tires stay more consistant during a 45min to hour long race.
[ Edit (added): and yes, they were running 245/45/16s on the 8s and 9s. ]
And also, my S had to weigh 2822, which is damn heavy. So it benefitted by having a fat tire to help it transition in corners.
Another note, I find that the 16" 245s will go off sooner in longer run sessions/races than the 285s. They start to get greasy and loose several laps sooner that the 285s. More rubber takes longer to heat up, and the tires stay more consistant during a 45min to hour long race.
09-14-2005, 01:42 PM
#74
Race Director
On my 2450 lbs 944 (2600 with driver) I have not noticed our 225/50 toyo going off at all during race. Well I take that back. If you overdrive the car the tires do seem to go away. However one or two laps that are not really slower, but with less sliding bring the tires right back their optimal grip.
With respect to the weigts it is one reason I would much rather race 944 at 2600 with driver than 2779 without the driver. That 350-400 lbs really makes a huge difference.
With respect to the weigts it is one reason I would much rather race 944 at 2600 with driver than 2779 without the driver. That 350-400 lbs really makes a huge difference.
09-14-2005, 02:04 PM
#75
Race Director
Originally Posted by Oddjob
In PCA Club Racing, I don’t recall that last time I saw a 944 on 15” wheels. The fastest guys that I know or ever saw in I Class 944s were running 8 and 9 x 16s Fuchs in PCA, but would put on the low profile 15s when they raced SCCA to meet the rules. Im assuming that these guys would have used the 15s in PCA if they thought they were a faster setup.
Also, as Joe pointed out, 16x7 wheels have been legal for these cars in SCCA ITS for a while now.