Mach 5

I'm looking for some inexpensive track wheels for a '86 951. They will be used for both Autocross and DE. My ideal would be a set of four 16 x 8 early offset Phone Dials which I could run 245/45s on. In my quest to find these, I have come across two interesting alternatives. Both are late offset and would require spacers/adapters, but I'm fine with that (I have run them on a '72 911 DE car for 14 years).

Option 1 - Late offset 951 Phone Dials, 7s and 8s. I'd have to run 225/50s on front.
Pros: light wheels, cheaper tires. Cons: smaller front tires.

Option 2 - 18 x 8 Cayenne wheels. I'd run 245/35s all around.
Pros: 245 "square" tire set up. Cons: Heavier wheel (+10 lbs, I think), more expensive tires.

I can get the Phone Dials for $100 and the Cayenne wheels for $150. So the real question comes down to which one will perform better. Smaller and lighter, or bigger and heavier? Better response versus better grip?

Thoughts anyone?

Thanks.
Roger

jmj951

I would vote for the smaller/lighter wheels.

At basically the exact same tire size, I noticed a difference between a set of 18" BBS OEM wheels (for 996) that I was originally using versus a set of 18" Forgeline wheels I used for my last two events.

Mach 5

jmj951,

When you say you noticed a difference, I'm assuming you are referring to the 18" Forgelines being lighter and therefore better? What was the difference like?

Thanks.
Roger

Cyril

+1

User 41221

Go for the lightest wheels you can find, and hold out for early offset if you can. You will feel the extra weight of the spacers, in my opinion.

Also, if you are auto crossing, you might really appreciate getting as small a diameter tire as you can find. Math wise, it has some nice advantages out of the hole.

rlm328

There are numerous discussions on advantages and dis-advantages of wheel and tire size. The major advantage of the 18-in wheel vs 16-in wheels is around slip angle. The 18-in tires have a shorter wall which corresponds to a smaller slip angle which has an effect on handling. 17-in and 18-in wheels behave about the best for this car.

Note that jmj was comparing wheels of equal diameter. You will need to be able to make some adjustments to your suspension if you go with a square set up, if not you will have some interesting over steer.

Mach 5

I appreciate the feedback. I'm leaning towards the 16s. I'm gonna take a look at them in the AM. If they're nice I'll get'em. For $100, how do you go wrong? (assuming they are straight and un-cracked, as promised).

We have Mille Miglia 17" Cup 1s on the car now. They look great, but I'm just a bit uncomfortable using these as track wheels with stickies. Autocross is one thing, but Road America is altogether different! They might be fine, but I guess I'd just feel a bit better with OE wheels of some sort.

Roger

jmj951

Yes, the forgelines are much lighter, and better on the track. I noticed it most during braking. I still have stock brakes (using Pagid Orange on the track) and had an easier time slowing down for the hairpin and the corkscrew.

Van

Bob, I'm pretty sure sidewall height has nothing to do with slip angle - sidewall flex has other implications regarding bounciness, grip and contact patch. But when it comes to slip angle, that is primarily dictated by rubber compound.

Remember that the spring value of the tires works in conjunction with the spring value of the suspension - and lots of people that put on 17" or 18" wheels without addressing springs/shocks/sway bars actually reduce their handling capability.

As a purist, I'm going to vote for the lightest wheel/tire combination you can put on there.

Mach 5

Good point. Right now it is basically stock suspension (horribly soft!). The plan is to modify the car in stages with my son, kind of an "automotive lab" project. I thought I'd start with a wheel choice, then move on to suspension, then possibly brakes.

Roger

rlm328

You are correct Van. But I was assuming tires from the same family which would similar tire wall variables, ie NT-01s. Most of the tracked 944's that I am familiar with have gone to the 17-in or 18-in wheels for a number of reasons, but handling is one of the primary ones, being able to cram in bigger brakes is why most opt for the 18-in over the 17-in, as tires are a little more expensive for the 18's.

As far as the 18-in wheels are concerned I will not disagree on a normally staggered set up, but he was talking a square set up. The square set up will shift the grip bias forward compared to the staggered set up.

From earlier this year:

https://rennlist.com/forums/944-turb...51-wheels.html

Search is your friend. Most anything you can think about to ask has been thought of and asked before. Like most forums it has a dynamic membership and these cars are old. People have been experimenting on them for thirty years so your questions are probably not unique, and may have the best answer buried from a true guru who is no longer participating in this forum years ago.

philstireservice

Aspect ratio in conjunction with compound does effect slip angle. A smaller aspect ratio will react faster to steering input as a tire with a stickier compound would. Compound trumps aspect ratio in most cases but the optimal combination makes for a smaller slip angle.

333pg333

You haven't mentioned if your car is stock or modified and if modified, how? I'm assuming it's pretty stock so I'd go with the PhoneDials being the lighter of your options. If the car is quite modified and has a lot more power than stock then I'd consider the 18"s and put on larger rubber.

Cloud9...68

It's very true that probably anything that can be said about wheel/tire choices has already been said, but I'll throw in my experience anyway. I have a mostly-track 968, with mild enhancements to the engine (so maybe 250 hp), and a full-race suspension (it has basically every component Racers Edge sells). I initially went with a staggered 18" set-up (8.5" wide fronts, 10" rears), but didn't like the fact that I can't rotate the (expensive 18") tires, so I picked up a set of 17 a 9" twists for $125 apiece, and mounted 245/40-17 BFG G-Force Rivals. I've only done one session on them so far, but I'm very happy with the result. It hasn't turned into a tail-happy handful as I had feared, and feels more lively thanks to the lower overall tire diameter in the back (I made the mistake of initially putting 285/35-18's back there, which are nearly 26" in diameter, vs. 24.7" for my new tires), and the significantly lighter wheel/tire combination in the back. And if anything, the car feels like it has more overall grip, not less.

I'm saying all this because you didn't mention 17" as an option. Unless you're running a ton of power, I don't think these cars need huge diameter wheels and wide tires, and I think 17" hits the sweet spot. My 2 cents, anyway. If only there were really lightweight 17" wheels available in our bolt pattern and offsets...

Van

Look at any "tried and true" track wheel for light 17"s : Fikse, CCW, Kinesis, Braid, Jongbloed, etc.