944 Wheel Questions

Attended my first AutoX this summer and am officially hooked (in a 1986 944 NA). This, of course, means one thing....upgrades.

I'm currently running the stock 15" phone dials but am unable to get any good rubber at that size (and the size of the sidewalls have gotten me a few chuckles as I pull up to the line). So i figure a new set of rims is just what the doctor ordered - possibly 16" or 17" depending on what is available.

With that said, does anybody have any suggestions for:

A) what rim dimensions I should be looking for (width, backspacing, etc,)?

B) any specific rim models I should be looking at that are affordable?

Any information would be greatly appreciated.

-Brew

If you want race rubber, any size wheel will work, because you can buy Hoosiers in all sorts of sizes.  Good high performance street tires, go 17.  The last remotely useful dual purpose 16" tire for a car of that size is a BFGoodrich, and you don't want to get laughed out of the Porsche owners club for running an American tire.

I am assuming a couple of things- 1, a 944 uses roughly the same size tire as my third gen Camaro, and 2, BFG still makes the SuperSport in a 245/50 16.

Go 17.

What class are you running? SCCA rules or local rules? I think that would determine what you need. If its your first few events keep your car as is and continue to autocross on the same setup. 

Porsche doesn't recommend larger diameter wheels than 17" on the 944 and those that do should have the 968 caster blocks along with more caster added to compensate.

That said, depending on the class, race rubber in 13-15" is readily available. You just need wider wheels.  Larger diameter won't necessarily help you due to the potential change in gearing.

Diamond Racing will make relatively cheap wheels to your width and offset desires.  The 5x130 bolt pattern is a hinderence for cheap wheels.

First figure out the class you'll be running and how close you can get to filling the fenders in width in tires that work for that class.  Then get wheels that will support them.

For example: The 944 can swallow 285's in the rear with a little rolling and 245's in the front.  Use Willitfit.com to model the current wheels and what potential new wheels might look like and transfer those potentials to the car with a tape measure and some poster board.

Porsche Turbo Twist wheels are plentiful and fairly cheap. Or just try some of the smaller cheaper Boxster wheels. I had a set of 16 inch early Boxster wheels and I had a hard time giving them away. They look good on 944s too. 

I put 16" "gulleydeckel" wheels on mine:

I was able to find Firestone Indy 500s in 16", but that was two years ago.

My car is an 85.5, so it has the early offset, so I'm running long studs and spacers.

In reply to aw614 :

There is actually a story behind the class I'm running - so the car is bone stock EXCEPT the previous owner ripped out the Catalytic converter. Thus, I'm currently running in C Street Prepared.

While this doesn't bother me currently since still new and more-or-less driving against myself, I'm going to have to figure out what I want to do with that sooner or later.

In reply to Stefan :

Thanks for the advice. I'll take a look through the rules and see what I can run. As I stated in my other post, I'm currently being put in C street prepared because of my cat being removed so I need to do some plannig to decid where the car is going to end up. I supose tire/rims will need to be part of that calculation.

Woody said:

Porsche Turbo Twist wheels are plentiful and fairly cheap. Or just try some of the smaller cheaper Boxster wheels. I had a set of 16 inch early Boxster wheels and I had a hard time giving them away. They look good on 944s too. 

The problem with that is he has an early offset 944 (+23ish IIRC) and all the wheels you just listed off are in the +50 range which means they either won't fit without ripping off the fenders or at least will look weird. Also there's at least as many options for 15" autocross tires as there are for 16", so he'd really need to go up to at least 17s to really get more options.

On my 87 944 I put Boxster wheels on it and viola.  The backspacing changed between 86 and 87 though.  I think Cayenne wheels may have a backspacimg that works for 86.  The 23-25mm backspacing on the 84-86 cars is a real bitch.  If you have cash custom wheels will be the way to go.

Here is good info on Porsche wheels:  https://www.alloywheelsdirect.net/information/fitting_chart/porsche

Or, you can do what I did:

90mm studs and 25mm spacers. My front wheels still sit a bit more inboard than I'd like, but it works.

Tom_Spangler said:

Or, you can do what I did:

90mm studs and 25mm spacers. My front wheels still sit a bit more inboard than I'd like, but it works.

I know lot’s of Porsche’s run big spacer setups.  I personally just don’t like it.  

In reply to dps214 :

Maybe I'm asking the wrong question then. Any suggestions on good AutoX/Street tires for 15x7 phone dials?

To note, the car is not a daily driver. I drive it to and from AutoX and to work from time to time.

You can update to late offset to solve those issues.  That would also allow you to update to 968 caster blocks which is completely legal as it is an update made during the production of the cars.

Porsche spent a lot of time and energy getting the front suspension as good as it can for the time with nearly zero scrub radius, etc.

So if you're going to spacers (I have a set for my 924 cum 944 to run 17" BMW wheels, the car is early offset and has 944 quarters), pay attention to the scrub radius to avoid changing the way the car behaves.  I put polyurethane caster block bushings in the front and increased the caster per the Porsche recommendation.

I'll have the adapters and wheels available to buy fairly soon as I have a set of 15" early offset cookie cutters wrapped in R-compounds to put on it along with a set of 17" early offset 5-spoke wheels, both of which get away from adapters and drop a bit of weight as that is important on a 110hp car ;)

AnthonyGS said:

I know lot’s of Porsche’s run big spacer setups.  I personally just don’t like it.  

I get it, I was hesitant, too. But the way I see it, with the longer studs, I haven't moved the "pivot point" of the wheel assembly. My spacer acts just like part of the wheel. It's not the same as a bolt-on spacer that the wheel then attaches to.

Having said that, if there's a better way, I'm happy to hear about it. This was kind of a cheap/quick solution to make these wheels work.

BrewCity20 said:

In reply to dps214 :

Maybe I'm asking the wrong question then. Any suggestions on good AutoX/Street tires for 15x7 phone dials?

To note, the car is not a daily driver. I drive it to and from AutoX and to work from time to time.

What are other people running in Street Prepared classes?  GRM does tire tests in the magazine pretty routinely and they can really help with tire determinations.

Personally, I'd go with either 205/50 or 225/45 R15's in R-compounds.  So the Hoosier A7, G-Force R1 S, Toyo Proxes R888R/RR all are available in those sizes.  If you can get a set of wheels made that are 8 or 9" wide, then you could go 245/40 or 295/35 wide tires in 15" diameter.

That said, I'd continue running what you already have and focus on learning Autocross skills and maximizing the existing traction from your existing tires.  Put a cat back on it and drop back to a more reasonable class, work on improving the driver and chassis.  Better shocks and spring rates, a lower center of gravity, a limited slip (if not already installed), a more aggressive alignment, etc.

Tom_Spangler said:

AnthonyGS said:

I know lot’s of Porsche’s run big spacer setups.  I personally just don’t like it.  

I get it, I was hesitant, too. But the way I see it, with the longer studs, I haven't moved the "pivot point" of the wheel assembly. My spacer acts just like part of the wheel. It's not the same as a bolt-on spacer that the wheel then attaches to.

Having said that, if there's a better way, I'm happy to hear about it. This was kind of a cheap/quick solution to make these wheels work.

Change the suspension to late offset.  The front uprights and control arms change and the rear just uses different hubs and rotors.  Grab them off a late-offset car (plyhammer parts and others routinely part cars out).

BrewCity20 said:

In reply to dps214 :

Maybe I'm asking the wrong question then. Any suggestions on good AutoX/Street tires for 15x7 phone dials?

To note, the car is not a daily driver. I drive it to and from AutoX and to work from time to time.

Any of the 200TW autocross/track tires: RE71R, RivalS are the fastest for autocrss, but I'm pretty sure all of them have 15" sizes. Hoosier A7s exist in a ton of 15" sizes but aren't the greatest choice if you're also street driving the car.

Also I realized I had a brain fart and was thinking about offsets backwards, wheel spacers will solve the early/late offset compatibility issue as others have stated. I wouldn't be afraid to run spacers, as long as the parts involved are decent quality and installed correctly.

Stefan said:

BrewCity20 said:

In reply to dps214 :

Maybe I'm asking the wrong question then. Any suggestions on good AutoX/Street tires for 15x7 phone dials?

To note, the car is not a daily driver. I drive it to and from AutoX and to work from time to time.

What are other people running in Street Prepared classes?  GRM does tire tests in the magazine pretty routinely and they can really help with tire determinations.

Personally, I'd go with either 205/50 or 225/45 R15's in R-compounds.  So the Hoosier A7, G-Force R1 S, Toyo Proxes R888R/RR all are available in those sizes.  If you can get a set of wheels made that are 8 or 9" wide, then you could go 245/40 or 295/35 wide tires in 15" diameter.

That said, I'd continue running what you already have and focus on learning Autocross skills and maximizing the existing traction from your existing tires.  Put a cat back on it and drop back to a more reasonable class, work on improving the driver and chassis.  Better shocks and spring rates, a lower center of gravity, a limited slip (if not already installed), a more aggressive alignment, etc.

Rookie question here. Am I going to have wheel size or suspension issues changing from the current tire size (215/60 r15) to either the 205/50 or 225/45s? Should it just be as simple as swapping the new tires on and hitting the AutoX course?

Spec 944 runs those tire sizes on the same wheels at much higher speeds and lower suspension height.

You should be fine.

you'll have a change in final drive due to the diameter difference and your speedo might be off a bit.