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How do you pick the best wheel/ tire size ?

PostPosted: Mon Mar 28, 2016 6:48 pm
by lrayner
For AX, is the widest, lowest profile tire that will fit generally the best performance option? Is an 18" wheel generally better (higher performance potential) than a 17" wheel? I have points to give so that isn't a big factor and information on what will fit (what options I have) is out there but it seems to be an underlying assumption to go as wide and low as you can. Is that the answer? I'm trying to decide if I should buy different wheels as well as tires.

My 968 has 17" cup wheels with well toasted 225/45 fronts and 255/40 rears. They also came with 16" wheels, and it appears that the 18" turbo twists with 225/40 fronts and 265/35 rears off my 2002 Boxster S will fit as well (but a swap won't work as the 17s hit the calipers on the Boxster I think). Would the 18" wheels and tires be a performance upgrade for the 968? Should I just get wider tires for the 17" wheels? Any thoughts on approach, other options to consider would be appreciated.

Re: How do you pick the best wheel/ tire size ?

PostPosted: Mon Mar 28, 2016 7:33 pm
by Steve Grosekemper
The short answer is there is no correct answer.
Yes, tires are the best way to go faster.
The set up for an AX 968 is 255/40-17's on 9x17 wheels square.
I would suggest RE-71R tires.

But that setup will have fender to tire contact with stock suspension.
With stock suspension use 235/40-17's on 7.5's or 8 inch wheels on the front.

Here are the steps in suspension upgrades: (In order)
-Mo30 sway bars F/R and triangiulated brackes in front,
-250lb front springs with lower spring perch kit.
-Koni single adjustible sport shocks. (F/R)

Other wheel tire options:
993 winter wheels 9x16 w/245/45-16 tires are a nice set up. Light and short for favorable gearing.
18-inch wheels are generally heavier and tires are more expensive. Not a good choice for an AX 968.
17-inch wheels will give you the best tire choices for 225-295 size tires.

Re: How do you pick the best wheel/ tire size ?

PostPosted: Mon Mar 28, 2016 10:01 pm
by ScandinavianFlick

As an alternative to M030/Konis, if you have points to spare, KW makes a V3 coilover kit for the 968. I've had V3s on my S2000 for five years and 40,000 hard miles, and have nothing but good things to say about them. They're very robust, the damping quality is excellent, and the adjustment range is sufficient to allow +/-25% spring rate without revalving (the increments are a little wide, but fine enough to be usable to fine tune the chassis balance). They're dual adjustable, which is important for Qualcomm's... unique surface (I run my compression settings near the bottom of the range, an option you wouldn't have with single adjustables).

Normally I'd say just roll the heck out of the front fenders to fit those 255's, but your 968 is WAY too perfect for that :D


Re: How do you pick the best wheel/ tire size ?

PostPosted: Wed Mar 30, 2016 8:42 am
by lrayner
Thanks Guys, now it is off down that slippery slope :burnout: