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Old 12-31-2013, 03:04 PM   #1
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I would suggest you spend some time checking the competition driving section over at Planet-9. From what I remember reading, the newer style ABS and PASM systems have to have a larger OD rear tire than front tire to function correctly. I don't think it matters what aspect ratio the tires have, as long as the computer sees more revs/mile on front than the rear.

If you want to reduce the understeer tendency with stock front camber, you can reduce the front to rear tire width stagger to something like a 245 front / 265 rear, or perhaps a 255 front / 275 rear.

Lots of good tire choices should be available allowing driving to the track, including Dunlop ZII, BFG Rival, Bridgestone RE-11A, Hankook RS-3, and Yoko AD-08, Michelin PSC's, etc. I have even driven to tracks on Nitto NT-01's and Hoosiers when no rain was expected.

Just look at all the specs on Tire Rack and carefully compare dimensions. Tire sizes are not uniform, so don't trust that a 245 is 245 mm wide, or the aspect ratio is exactly what is says on the tire.
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Old 12-31-2013, 03:54 PM   #2
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Yes, you have to be careful of the relative diameters. I went up a size to 245/40 Fronts on my 987, and if I increase the pressure above 30 it's enough to make the PSM kick in.
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Old 01-01-2014, 11:35 PM   #3
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Move up in sizes.. A 275 easily fits on the rear.. and a 245 easily fits on the front.

Tirerack and others list the actual diameter of the tires. Do the best you can to get as close to stock as possible.

I'm worried the car has a specific 19inch program in it
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