Tire Size vs. Rim Width

[mickf]

Are there serious downsides of running 245/45-17 Kuhmo 710s on my 10" wide rear wheels for autocross? Kuhmo specs are for 7.5-9" wheel width. Are there real safety concerns or real performance issues if the wheels are an inch wider than specified by the manufacturer? Since they'll only be used for autocross, the added potential for curb rash isn't really a concern.

Running 245s all around seems to be the proven setup for autocross Boxsters, so I'm trying to figure out whether I'll be OK or need to go with 275/40s in the rear.

Thanks!

[Highlander]

245 on a 10" wheel is pushing it. I have run 225's on 9's and it was a serious squeeze. 245 on a 10 is even more of a squeeze.

Having said that, they will fit and you can run them. The combination of lack of camber and sidewalls angles inwards will cause seriously accelerated wear on the out er 1/2" of the tire.

You would be better to acquire another set of wheels. 9" wheels work well with 245's and wih the correct offset, you can easily run 9's on all four corners.

Graeme

Edited November 22, 2005 by Highlander

[mickf]

I was afraid of the answer, but makes sense. Those tires are too expensive and sure don't need serious acceleration to wear out quickly. They do that just fine on correct wheels.

Appreciate the input!

[Highlander]

You are welcome.

I destroyed a set of Michelin PS2's in short order by squeezing 225's on 9" wheels.

Graeme