What tire size would be best for the following wheels (on the way)? I have a coilover suspension if it matters.

Fr: 18"x8.5" +40
R: 18"x9.5" +40

Obviously I want the widest ones that will fit.

Thanks
Alan

 

245/45 front, 275/35 rear.

 

Wrong size up front!

Proper tire sizing up front would be 235/40 or 245/35. Ideal rear sizing would be 265/35, but you could get a 275/35 to work decently.

 

I have 235/40 front and 265/35 rear

 

Thanks for the help. I looked up a tire size calculator and here's what I came up with, when trying to keep the circumference the same as stock.

Stock (not really)
245/45-16: 77.5"

Front:
235/40-18: 79.8"
245/35-18: 77.8"

Rear:
265/35-18: 79.5"
275/35-18: 80.4"
275/30-18: 77.0"

So it looks like 245/35-18 and 275/30-18 (if such a tire is available) would be closest to stock circumference.

 

I wouldn't look at circumference when comparing tire sizes. Instead, look at the overall diameter. It's much more meaningful. Also, it's better to use the actual manufacturer's dimensions for the tire. You can compare these at www.tirerack.com You will be surprised to see the size variations of the same size tire from different manufacturers.

And no, they don't make a 275/30 18 tire....

 

Thanks again Rynberg.

Has anyone used a 285/30-18 on a 9.5 inch rim? I know it's the typical size for 18x10.

 

I suppose you can get it to fit but most manufacturers recommend a 10-inch wide wheel as the minimum. I wouldn't do it. There's no point in going with wider tires if there's no rim width to support it. Stick with the 265/35s in the rear as they will be a) cheaper, b) handle better, and c) look better IMO.