Aurion ATX & Rims & tyre opinions/questions

[stedyedy]

Hey all,

Ok so basically i have an ATX with 16" alloy's

I recently bought a pair of 18" rims with tyres 235/40/R18

From that tyre size calculator this is what is says

When your speedo reads 100km/hr you're actually at 93.69 km/hr

is this to big of a difference?

also i have just realised (correct me if i am wrong)

but in terms of stock wheel circumference the ATX has the biggest?

And one more question

Is there any difference between

235/50/R18

and

235/40/R20 wheels they basically have the same rolling circumference give or take a few CM so the spedo be very accurate?

i read a few posts on the forum and some people have said on stock aurion get 18" or 19" rims but i can see the difference between bigger rim lower profile and smaller rim bigger profile??

any finally

Whats the deal with the spare tyre?, since i am aiming to get a very similar rolling circumference i assume if i get a flat i can use the spare as i normally would.

but what about all those pepople who have much larger circumference can they just stick on the spare aswell??

thanks in advance

Cheers

Edited October 9, 2009 by stedyedy

[DJKOR]

I recently bought a pair of 18" rims with tyres 235/40/R18

From that tyre size calculator this is what is says

When your speedo reads 100km/hr you're actually at 93.69 km/hr

is this to big of a difference?

Which calculator did you use? From the tire calculator I use says 2.941% too fast meaning that when your actual speed is 100km/h, your speedo will read 102km/h. This is the one I use:

1010 Tires - Tire Size Calculator

So long as you stay within 3%, you should be fine. You can go outside of this, but when you do that, you start to play around slightly with handling and braking.

but in terms of stock wheel circumference the ATX has the biggest?

Actually the Sportivo does:

AT-X: 215/60R16, Diameter: 664.21mm, Circumference: 2086.6mm

Sportivo: 215/55R17, Diameter: 668.27mm, Circumference: 2099.3mm

Is there any difference between

235/50/R18

and

235/40/R20 wheels they basically have the same rolling diameter give or take a few CM so the spedo be very accurate?

To answer that specific question, the only difference is 3.81mm in diameter and 11.9mm in circumference. These tire sizes would not be recommended however.

[stedyedy]

thanks for the answer, for some reason i thought the ATX had tyres 215/65/r16

but now have changed the first post

Cheers

[SecaBoy]

according to that site daryl, when im going 100, i'm only going 96... and yet i seem to be going faster than everyone else on the freeway...

maybe i'm not doing it right...

stock - 245/35/R19

new - 245/35/R20

oh, the rears are still 245/30/R20... but that wouldnt make any difference to my speed, would it?