Neil64

Hello All,

I picked up a set of ASA AR1 wheels for my 01 GS430. They are 18x8 +35mm offset. They came with Bridgestone Potenza RE050A 225/45/18 tires. Wheels and tires are about 2 -3 months old and have about 500 miles on them.

I am currently running 17x8 OEM 5 spokes with Goodyear Eagle F1 GSD3s in 235/45/17 with about 10K on them..

Tirerack and other sites recommend a 245/40//18 for the GS.

225/45/18 is 25.9 in diameter
235/45/17 is 25.4 in diameter
235/40/18 is 25.4 in diameter
245/40/18 is 25.7 in diameter

When comparing the new 225/45/18s (32psi) to my used 235/45/17s (38psi), there is close to an inch of height difference. I tried the new rims and tires on the drivers side of the car and the car was noticably higher on the drivers side. I'd like to at least try the 225/45/18s as they are brand new and paid for. Even if I was to remove them and try to sell them, how much could I get? They run $212 each.

Here are my questions:

How far can you straggle away from 25.4 diameter before you are considered out of spec? I assume this will affect the speedo and odometer.
How can I calculate accurate speed and mileage? Are there any tables online that can be used?
Will running a 225/45/18 adversly affect VSC or the ABS?
Can I still use a worn 235/45/17 for a spare while running the 225/45/18s?

Thanks...

Neil

rominl

iTrader: (4)

well that's just like those of us with 20s and running overspec tires. speedo would be off but that's about it. i don't really worry much about it

now your car being higher.... come on, just lower the car

about the spare, i would say yes, it's just like you using a donut spare on some cars. you just aren't supposed to use it for a long time

rominl

iTrader: (4)

i think speedo wise it's only very little. for example when it says 80mph, you are actually doing maybe 83-84mph