Tire Sizes
07-11-2002, 10:56 AM
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Tire Sizes
I'm running 225/45-17 front and 255/40-17 rear on 7.5" and 9" wheels. The tires have not held up well under track abuse, and I'm considering using the Falken Azenis Sport. This tire is made in a 225/45-17 (looks huge compared to my current 225's) and 245/45-17 (looks as wide as my current 255's), but that's it. But the 245/45 is .6" taller than the 255/40. Any ideas what impact this would have (other than taller gearing)? I had my car aligned/leveled with the current setup, so now the rear would be .3" taller. Any impact on alignment/handling? On the ABS?
I considered the A032R as well, but the reverse problem exists - the closest front available is a 235/40, which is shorter and too wide for a 7.5" rim.
Gary
89 951
I considered the A032R as well, but the reverse problem exists - the closest front available is a 235/40, which is shorter and too wide for a 7.5" rim.
Gary
89 951
07-11-2002, 12:29 PM
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well....first...use a race tire for track use and life will be much better.
describe the wear problem? is it camber related?
Finally, 9 inch rims will easily bolt on the front of that car...if you upgrade the rim, and run a shorter stiffer wider tire, you will have better turn in, better braking and better tire wear.
describe the wear problem? is it camber related?
Finally, 9 inch rims will easily bolt on the front of that car...if you upgrade the rim, and run a shorter stiffer wider tire, you will have better turn in, better braking and better tire wear.
07-11-2002, 06:51 PM
#3
Race Director
"The tires have not held up well under track abuse, "
What do you mean by that? I think track-racing will 'abuse' ANY tire. The one that has held up the best for me has been the BFG CompT/A VR4. But with a treadwear-340 rating, it didn't quite stick like glue either. The Yokohama A032Rs are easily 10x better (about 10sec/lap faster), but they only last about 5 race weekends.
So are you running at least -3 degrees camber in front and -2.5 degrees in rear? If you don't have upgraded springs & swaybars, you might need to add another degree of negative camber on top of that even. Insufficent camber is probably the largest contributor to 'tire abuse'...
What do you mean by that? I think track-racing will 'abuse' ANY tire. The one that has held up the best for me has been the BFG CompT/A VR4. But with a treadwear-340 rating, it didn't quite stick like glue either. The Yokohama A032Rs are easily 10x better (about 10sec/lap faster), but they only last about 5 race weekends.
So are you running at least -3 degrees camber in front and -2.5 degrees in rear? If you don't have upgraded springs & swaybars, you might need to add another degree of negative camber on top of that even. Insufficent camber is probably the largest contributor to 'tire abuse'...
07-11-2002, 08:37 PM
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Yes, I am using street tires on the track, and no, I'm not running that much camber. The wear patterns and temps don't seem to indicate a need for more camber, but I'm sure it wouldn't hurt (currently, -2.5 front, -2 rear). Suspension is stock for a '89 S, and the car was very neutral last time out.
Since one of the tracks I frequent is 100miles one-way and I don't want to swap tires, my choices were the Falken, A032R, or Toyo RA-1. If you can believe it, none of these tires are offered in both 225/45 and 255/40. The Falkens are inexpensive and I'd bet not much slower than the other two tires.
But anyway my question is really whether a 25.0" and 25.6" (vs 25.1) rear tire combination will cause a problem. Don't think it will impact camber, toe, etc, but it will raise the center of gravity in the rear a bit. Hopefully, not enough to disrupt the balance of the car.
The 225 Falkens are wider than my current 225's and the 245 Falkens about the same width as my current 255's. But they have much larger tread blocks, stiffer sidewalls, and softer tread. The only thing that really concerns me is the taller rear.
Since one of the tracks I frequent is 100miles one-way and I don't want to swap tires, my choices were the Falken, A032R, or Toyo RA-1. If you can believe it, none of these tires are offered in both 225/45 and 255/40. The Falkens are inexpensive and I'd bet not much slower than the other two tires.
But anyway my question is really whether a 25.0" and 25.6" (vs 25.1) rear tire combination will cause a problem. Don't think it will impact camber, toe, etc, but it will raise the center of gravity in the rear a bit. Hopefully, not enough to disrupt the balance of the car.
The 225 Falkens are wider than my current 225's and the 245 Falkens about the same width as my current 255's. But they have much larger tread blocks, stiffer sidewalls, and softer tread. The only thing that really concerns me is the taller rear.
07-11-2002, 10:45 PM
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Nah, don't worry about the higher rear. You can lower the ride-height 0.25" to make up for it if you really want to. I'm running a 255/40-17 and 275/40-17 combo and haven't had too many problems on the track. I wish someone would make the proper-diameter size of 295/35-17 though...
07-12-2002, 12:39 AM
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Cool...I'll give it a shot. Looks like you have the same tire diameter difference front/rear, Danno. 255's on the front? That's huge; no way it would work with my 60mm offset wheels.
Checking the height of front/rear suspension components, it seems like the rear is a little low anyway.
How about any effect on the ABS from the different tire diameters? Guess I could always pull the relay to disable it anyway.
Checking the height of front/rear suspension components, it seems like the rear is a little low anyway.
How about any effect on the ABS from the different tire diameters? Guess I could always pull the relay to disable it anyway.
07-12-2002, 12:48 AM
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Gary,
I have been running 235/40/17 on the front 7.5" C2T replicas with not problems at all. Most sizing charts show it to be an allowable combo - the 95 M3 ran that combo stock.
I actually find it a quite pleasant combo 235 fr and 245 rr. No more understeer problems, and the car doesn't tramline too bad at all. I am running el-cheapo Yoko AVS intermediates (on clearace at tirerack for <$70 per corner).
Eugene
I have been running 235/40/17 on the front 7.5" C2T replicas with not problems at all. Most sizing charts show it to be an allowable combo - the 95 M3 ran that combo stock.
I actually find it a quite pleasant combo 235 fr and 245 rr. No more understeer problems, and the car doesn't tramline too bad at all. I am running el-cheapo Yoko AVS intermediates (on clearace at tirerack for <$70 per corner).
Eugene
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07-12-2002, 04:18 PM
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Actually Eugene, most of the sizing charts, including Yokohama's, show a minimum 8" for a 235/40-17. I've always believed using a narrower tire that fits the rim better is preferable to a wider one; the sidewalls are more effective and the contact patch is optimized.
But, I've heard from several people who seem happier with similiar front/rear tire sizes to reduce understeer. Another '89 at the local tracks runs 8" front, 9" rear with 245/45-16's all around.
btw, I put the 225 Falken Sports on the front already and there was a noticeable improvement in turn-in and braking. Waiting for the 245's to arrive any minute... (of course violating one of the basic rules of racing .. don't make modifications the day before an event!)
Gary
Gary
But, I've heard from several people who seem happier with similiar front/rear tire sizes to reduce understeer. Another '89 at the local tracks runs 8" front, 9" rear with 245/45-16's all around.
btw, I put the 225 Falken Sports on the front already and there was a noticeable improvement in turn-in and braking. Waiting for the 245's to arrive any minute... (of course violating one of the basic rules of racing .. don't make modifications the day before an event!)
Gary
Gary
07-16-2002, 12:48 AM
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In case anyone is interested in an inexpensive dual-purpose (street/track) tire, the Falken Azenis Sport is great. I tried them on the track this past weekend, and could stay with most cars on Kumho Victoracers in the corners. The tread blocks didn't feather and the rubber was soft and sticky. Problem is limited size availability - I had to use 225/45-17 front, 245/45-17 rear.
Front tires were definitely too hot on the outside shoulders and the car did push a bit so I'm going to add at least another half degree of negative camber in front.
I expected the taller rear tire (25.7" vs 24.9" front) to cause a problem but I'm not sure it did. I may lower the rear a bit anyway. I looked at earlier threads on ride height and some suggested level front/rear, others slightly higher in the rear. Any thoughts on this?
Anyway, thumbs up on the Falken's. The fastest street tire I've ever tried.
Front tires were definitely too hot on the outside shoulders and the car did push a bit so I'm going to add at least another half degree of negative camber in front.
I expected the taller rear tire (25.7" vs 24.9" front) to cause a problem but I'm not sure it did. I may lower the rear a bit anyway. I looked at earlier threads on ride height and some suggested level front/rear, others slightly higher in the rear. Any thoughts on this?
Anyway, thumbs up on the Falken's. The fastest street tire I've ever tried.
