Wheel Size

[chrislak]

I was wondering if someone could shead some light on what bigger wheels will do to performance say you were to install 20inch wheel on the XR6T, would you gain take off speed and loose top end or is it the other way around.

[Turbo6man]

20 inch wheels work good on busses.

If you change rim diameter you change tyre profile to suit - so the overall diameter remains the same - there is no difference in performance when you do this.

However if you keep the same profile tyre on to the 20 inch rim you will have less accelleration, theroretically a higher top speed, and a speedo that reads way below your actual road speed - a good way to becoming licenceless quick-time

[cdm]

Ride will be firmer and handling I suppose better but the tyres would cost a fortune! and the rims for that matter!

[daninme]

correct the bigger the wheel the more revolutions. and correct slower take off but higher top end.

my mate bought 19s on his wrx and blew his diff in less than a week.

[Guest mrmods]

hahahahahahaha its amazing how many people know nothing about cars

[turbo_nick]

several points...

1. there's no chance in hell you could retain the same rolling diameter with 20s

2. they'd be sort of legal

3. they would make the car slower

4. good luck finding tyres! hehe

unless you want the wheels and tyres for shows only, I wouldn't even bother with 20s. 19s would work magic on handling but not ride comfort.

fyi - tyre size and rolling diameter in mm

235/45/17 = 643.3

245/40/18 = 653.2

245/35/19 = 654.1

245/30/20 = 655

whoa! I thought 20s would be too big for a Falcon - as in illegal.

*thinks about the 20" raptor rims at work*

hehehehehe

[Superoo]

And I thought I was being far too pedantic when I made the same rolling diameter calculations....

Definitely agree the diameters would be different.

But seeing it's been bought up, I do have a couple of questions.

1) Whilst I got the same figures, are we not assuming the same sidewall flex in each case? As small as it would be, wouldn't an 18 inch tyre with its smaller profile flex less than an equivalent 17 at the same pressure? Would this mean the difference in rolling diameters between 17's and 18's is slightly greater than the 9.9mm suggested?

2) As my steep driveway allows bugger all clearance for that awesome exhaust, would I actually increase ground clearance by opting for the 18's? (I have no intention of doing this, just interested).

20" rims? The price of 18's was enough to scare me off.............

[chrislak]

Thanks guys for your responses they have helped, so do I read this correctly are XR6's with 18 inch wheels actualy slower at take off than one fitted with 17 inch wheels, I suppose the proper way of installing very large diameter wheels is to change the diff ratio to composate for the extra diameter and possibly a step down/up gear for the back of the speedo.

One other point how would the wheel bearings react to 20 inch wheels.

Woudn't car would look at of this world with 20"s.

[Guest LionHeart]

Not sure I would be a fan of 20's on an XR..

The T in the XR6 is TURBO not TRUCK.. that's my opinion anyway.. Its not something I would follow up.. 18's I think would be th elimit of my imagination, 17's are doing me more than fine...

[CJF077]

20" rims on an XR6T