Tire Size from 17 to 18, Please Assist :)

[UltArc]

Hey guys!

Alright, heres the deal. Current Mustang is the stock wheels and rims, but I want to order the 18's from the GT.

So, my tires are these: P225/60R17

Found here: 2012 Ford Mustang V6 Coupe 3.7L V6 6-speed Manual Features and Specs

And this is the size I want to switch to: 235/50R18

Here they are: 2005-2012 MUSTANG GT - 18" WHEEL/TIRE SET - PIRELLI TIRES - OEM TAKE-OFF (NEW) | eBay

Now please keep in mind that I know very little on the topic. I did quite a bit of research, but I think I am not super clear on figuring out what to search for. Most of what I found involved large SUVs upgrading there rims, and the other things I found were of no help. Most people don't care about mileage, or ride, or how the vehicle can move with improper tires.

My concern is my spedo, and vehicle in general, regarding gauges and info. I know I can edit the info on the gauge, but my concern is keeping it correct. Clearly these fit, as the GT and v6 are almost identical. SO, can anyone help me with this?

The v6 wheels are going to become track tires, the GT rims/wheels are for daily driving, and I am getting some blizzacs for winter with some plane jane aluminum wheels.

So guys, please, help me out?

[ksa8907]

2.3% faster than stock. 60mph would be 61.38. If you google search "miata tire size calculator"

[UltArc]

Originally Posted by ksa8907

2.3% faster than stock. 60mph would be 61.38. If you google search "miata tire size calculator"

Do you know anything off hand about having the vehicle modified for the difference? Having the spedo recalibrated?

[mcrews]

did you search here on the site????????????
bet ther are 50 threads conerning tire size.
I know because i have started some and posted on others.

2.3% is just barely over the wear rate between a new tire and completely wore tire.