I have an 06 GT with stock 235 50 X 18" tires. The car has been lowered via an Eibach Pro-System Plus suspension kit. What would be the widest tire I could put on these stock rims? Also, would the tire swap impact the speedometer in any way?

 

255-265

 

I'm planning on putting 275/40 nitto 555 on my stock rims... everyone says it wont fit, but nitto specs says it requires a 9 inch rim, and I have a friend that had 275 eagle f1 gs d3s on his stock mach 1 rims.. which are 8 or 8.5 inches wide... so it's doable, they will just stick out...

 

Correct they fit....275 is just not reccomended and can become a safety concern later on.

 

i have 275/40 drag raials mounted on my stock tires. I would not take any fast turns on
them.

 

Hi jmart69x,

If you have the stock 8.5"x18" wheels you can put a 255/50x18 on them. If you go wider you run the risk of poor handling and the tire bead breaking and an instantainous blow out. This is obviously dangerous and is not recomended by any tire or wheel company. If you think you want a wider tire you must buy a wider wheel to support the tire sidewalls so the tire will perform and operate as designed. The wheel and tire makers have a standardized set of design parameters so they all work togeter safely and properly. To go outside of thes industry standards is to ask for trouble and endangers you,your passengers and the other people on the road around you.

Hope this helps!

 

...and be a potentally fatal error on your part when you have the tire bead break loose and instantly deflate your tires when they are under cornering load. Follow the wheel and tire makers guidelines and you will be rewarded with better cornering performance, tire life and safety.

HTH!

 

jmart69x

255/45/18's are the widest tire you can safely put on 8.5's.

As far as the speedometer question goes, you have to maintain a tire circumference of about 27.25, which is the circumference of your stock 235/50/18's. To maintain tire circumference when one puts on wider tires, one lowers the profile (assuming the size of the rim is constant). Hence 235/50/18's have a circumference of 27.25 and the wider replacement, 255/45/18 have a tire circumference of 27.03 or less than a1%differencevs the stock tire circumference.Up to 2% is considered acceptable. So the answer to your question is, if you correctly size plus tires you need not worry about re-calibrating your speedometer.

I am running Goodyear Eagle F1 GS-D3 VBs, 2555/45/18 on stock rims and they work really wellwith my suspension mods (see sig below).

Here is a link to a tire calculator.
http://www.1010tires.com/tiresizecalculator.asp

Good Luck!