Hey Guys,

So hypothetically speaking, if you were to have 18in tall and 9.5in width wheels all the way around and put 265/35/18 in front and 275/40/18 in rear for tires, would this cause any undesirable issues aside from speedo differences. I noticed that the rake of the car will be changed with the front being slightly further down than the rear. I calculated the differences of overall diameter and got this:

Front
110mm sidewall or 4.3in

Rear
92.75mm sidewall or 3.65in

So that means front OD(overall diameter) would be 4.3x2+18=26.6in.
Rear OD would be 3.65x2+18=25.3in.

Difference of 1.3 inches front to back. I've had them on before and didn't see any Traction Control or ABS issues. I just wanted to see if anyone has seen any adverse effects such as performance when doing this. Thanks in advance.

 

You have that backwards (at least according to what you wrote highlighted in paraphrase)...

225 45% 18 25.97 Stock Reference Size
245 45% 18 26.68 Stock Reference Size

245 40% 18 25.72 Front-Best Alternate
255 35% 18 25.03
255 40% 18 26.03 Front-2nd Best Alternate
255 45% 18 27.04
265 35% 18 25.30
265 40% 18 26.35
275 35% 18 25.58
275 40% 18 26.66 Rear-Best Alternate
285 30% 18 24.73
285 35% 18 25.85
285 40% 18 26.98 Rear-2nd Best Alternate
295 30% 18 24.97
295 35% 18 26.13
295 40% 18 27.29


You can probably skate by with the 265/35 F & 275/40 R without ABS, TCS errors. However, that front is really short by some .67"; but lots of people run 'em in that size with no probs.

Personally, I yanked a set of 265/35s off the RPF1s I bought several months back because, #1 - It looked funny to my eye, and #2 the tires (RS3s) were horrible riding and skated around a lot on me. (Not an issue related to your question but just a data point bit o'bishin' on my part.)

 

If you have the tires run them, if not , I would select a different sized front tire

 

Yeah I just noticed that my numbers were backwards. Doh! Thanks for pointing it out and thank-you for the reference numbers. That's very helpful and is much appreciated.

 

Yeah they are not on the car but they were already ordered. I'm going to try to go with a different set up next time. I might do 255/40/18 fronts and 275/35/18 rears. What do you guys think?

 

Look at the table of sizes posted up above. The GATP (generally accepted tire principle ) is 245 OR 255/40 and 275/40 (not 35 aspect, too short). You're right on the diameter mark with those.