With 225/45/18 tires coming standard on stock rims, I know 245/40/18 tires are within specs for speedo purposes. Does anyone know if 245/40/18 tires will fit on the stock OEM 18" rims properly or do I have to go with 235/40/18 tires?

Thanks

 

245 will be fine

 

We have 245-40-18 Kumho Ecsta SPT's on our stock wheels right now. Fit great and look much better than those Miata size tires they stick us with.

btw we had 265-35-18 Kumho Ecsta V700's on the stock wheels for some time, no problem with fit at all.

 

Noob question alert...

If you change to those 245/40/18, will that throw off your speedo?

 

the speedo will be off by about 1%.

http://www.1010tires.com/TireSizeCal...?action=submit

 

A bunch of us are driving on PZero Neros that are 245/40/18, and no one has reported problems.

 

Thanks...

Now to get another set of 18"oem's (as cheap as possible - road rash OK), refinish them and go from there.

 

good luck, i have been trying to do that on here for a month.

 

Tire Size Sidewall Diameter Circumference Rev/Mile Difference
225/45-18 4.0 in. 25.97 in. 81.59 in. 777 0.0%
235/45-18 4.2 in. 26.33 in. 82.71 in. 766 +1.4%
245/40-18 3.9 in. 25.72 in. 80.79 in. 784 -1.0%
255/40-18 4.0 in. 26.03 in. 81.78 in. 775 0.2%
265/35-18 3.7 in. 25.30 in. 79.49 in. 797 -2.6%

 

Thanks again.

 

I was going through the same decision process. The stock RE050s were worn out by 16,000 miles (and one trip to the Thunderhill track).

I went with a conservative 245/40/18 all around to keep the car balanced. Here in NorCal, I don't have to worry about snow (I do not miss driving in snow/ice/sleet from my days in New York).

We do get rain (a lot right now) so I decided to try the Goodyear F1s and bought four at Tire Rack. I can hardly wait until try are broke in

 

Based on those calculators, 255/40/18 would be the closest to stock. Does that not
- rub (shouldn't if 265 worked I guess)
- put extra stress on the steering mechanism/servo
- cause worse fuel economy than the stock size?