my01liberty wrote:

hey all
in the next month or two ill be putting a set of 18inch rims on my baby
but alot of people have been telling me:angry2:  the bigger the rims the more your speedo will be out :Dntknw: is this true or not help!!!!!:help:

depends. fit bigger wheels, you car will be travelling faster than what's showing.
fit smaller wheels, car will be travelling slower than what's showing.

best to stick with OEM size.

if you don't know what that is, open the driver's side door, there should be a sticker there displaying that information.

if you really want to go 18's, consult a wheel and tyre place. they should be able to help.

You can change rim size and tyre width and profile, but what the guys at a tyre place will be able to tell you is how close your new choice is in rolling diameter to the OEM size combo.This is after all what affects differences in speedo readings.

my01liberty wrote:

yea kool cause thats wat i thought cause your rim gets bigger
and your tyres get smaller therefore not changing the overall revolution of the wheel
so if your wheels r still the same revo then how can it stuff your speedo:Dntknw:

that's the easy part, sunshine.

the fun part is to now find wheels, and tyres that will maintain the same rolling diameter, and that's the right offset, and won't scrub...

the choices then are reduced significantly...(depending on how big your wallet is)!

my01liberty wrote:

yea kool cause thats wat i thought cause your rim gets bigger
and your tyres get smaller therefore not changing the overall revolution of the wheel
so if your wheels r still the same revo then how can it stuff your speedo:Dntknw:

If the rolling diameter is the same as the OEM wheels it won't affect your speedo. But depending on how much larger you want to go, it will be difficult to maintain the same diameter.
For example if you've got fairly low profile 16s from the factory, you'd be very hard pressed finding a wheel/tyre combo at 18" and still maintain the original diameter...

Go to The Tire Size Calculator and put in the size of your wheels and tyres you have on now.
Then put in an 18" wheel and find what profile tyre gets as close as possible to 0% difference.

Example, my Outback had 205/60/R16 on it when I got it, I put on 18" wheels with 215/45/R18 tyres, the Tyre Calculator comes up as saying the speedo will be reading 0.3% too fast, couldn't get any closer than that.

but then again yourv got to take into consideration that your speedo is by default a certain percentage below what your actualy doing.

If you're going for 18's, 205/40/18 would be the closest match to OEM - it's only throw your speedo out by about 1/2km/h - just comes down to what you can afford really!

Don't think so.