Tyre/wheel sizes .......?

[markrzs]

Hi folks, could anyone pls tell me if I could fit 285/40/18 tyres on my 18jx9.5 rims, I have 265/35/18 on them at the moment.

 

Any advice is much appreciated

 

 

Regards Mark

[Homer]

They will fit but will give too large a diameter for the supra, meaning your speedo (amoung other things) will not work correctly.

 

I think that 285/35/18 is the right size

[markrzs]

Thanks for getting back so quickly........what else would not work properly and wold the speedo be out much ?

[Homer]

An incorrect tyre size will affect the speed at which the active spoiler deploys, the amount of power assistance you get in the steering, the odometer accuracy and the gearing of the car (possibly slower acceleration).

 

Try this Excel sheet to find out the best tyre size (shamelessly stolen from Thorin, hope he doesn't mind!!)

 

http://www.kulthea.net/fitment.xls

[Lez]

Hi folks, could anyone pls tell me if I could fit 285/40/18 tyres on my 18jx9.5 rims, I have 265/35/18 on them at the moment.

 

Any advice is much appreciated

 

The stock wheels are 17s

8JJ 235/45/17 and 9.5JJ 255/40/17

making the rolling diameters 643mm & 636mm respectively.

 

Therefore best size for 18s are

235/40/18 = 645mm and

255/35/18 = 636mm

 

The recommended deviation is 2.5% so the max oversize is;

Front

245/45/17 = 652mm +1.4%

245/40/18 = 653mm +1.56%

245/35/19 = 654mm +1.71%

Rear

275/40/17 = 652mm +2.52%

275/35/18 = 650mm +2.2%

275/30/19 = 648mm +1.89%

 

The ones you want to put on are +7.7% 285/40/18 =685mm

I don't think 285s will fit 9.5 rims anyway

 

The tyres you have on now imo are spot on +1.1% 265/35/18 = 643mm

 

Hope this helps