Luke714

Hello,

First, let me say that I have never switched out a set of wheels. I understand the basic concepts of offset and backspacing, how read tire sizes, etc, but have no experience determining if a new tire/wheel combination will work on a specific car.

I have a 1986 951 that I love, the engine died and I spent a year switching in a 2004 LS1. Everything runs great, but the 225 rear tires aren't up to the task. Someone suggested using some C4 ZR1 wheels. I liked this idea because they're only 17" in diameter, I'm not a fan of really low profile tires; I want a little sidewall. I can also get my hands on a set for four wheels for very little money, relatively speaking.

1) Will the rear 11" wheels fit a 295 tire and the front 9.5" wheel fit a 265 tire well? I understand the need to match the wheel width with tire width, but do these seem like good match ups?

2) Has anyone ever done this?

3) Is there any immediate opinions on whether this configuration will work? I can roll my fenders but I don't want to change my fenders. I also don't mind getting rid of fender liners. I've got coilovers on the front as well. The car has been lowered about 1.5"

4) Many of the threads discussing wheel fitment are a little overwhelming and over my head, are there any good sources/references to read that will get me up to speed. I'd love any recommendations on extra informative and good wheel threads.


Thanks for your patience!

Luke

Paulyy

will the bolt pattern fit first

Jfrahm

On an 86 you would have lots of room for a hub adapter to expresses whatever bolt pattern you want. However these would cost enough to make you wonder if you shouldn't locate wider Porsche wheels instead.

What options are out there for early offset 17x10 wheels or the like?

OP: do you have an LSD trans? Also be aware once you hook the tires you really start to break stuff.

-Joel.

J Berk

I think you can probably find several OEM wheels from other P-cars that would fit your bolt spacing before going to a GM wheel configuration.

Go to the Wheel Enhancement website and look around

Luke714

Thanks for the fast replies. I didn't know about the wheel enhancement site, great place! I might give them a call and just talk about my options.

I can get high quality spacers for quite cheap, so I don't think they're much of a barrier. What are the widest tires that have historically been able to fit under stock fenders?

I have put a brace on the tranny to try to eliminate axle problems as those seem to be one of the biggest areas of failure. I also added a reinforcement plate to the tranny to help strengthen that week point: http://stweb.peelschools.org/sssweb/...tep/index.html
Other plans include a LSD or TBD asap, but I don't have the money. The reason I'm doing tires and wheels now is that I need new tires to pass inspection and I don't want to buy new tires for my phone dials.

pontifex4

Adapters tend to be heavy, which I suspect is why you don't see many on this sort of car. Post some pictures of your work!

YoungerThan944

You'll find more information on the widest wheels you can fit and related high-power upgrades in the 944 turbo forum. https://rennlist.com/forums/944-turb...bo-s-forum-72/

F40LM

Yes you will need a aset of adapters, either that or swap out the rotors hat etc and have them custom mounted to you 944. If you go the adapter rout make sure you get them at least centric to the car and preferably centric to the wheel. I know it can be very confusing. If you are already feeling confused then my advice is to find you a set of 17" wheels already witht he early offset set up.

I recently went to a set 18" anteras, seller (A PORSCHE PARTS PLACE IN ATLANTA) told me they would fit my '86 944 with the included 1" spacers for the wheels. Truth was this....they did not include the longer studs I needed for the rears, and the 1"spacers are actually 20mm spacers from porsche. So, I now am buying a set of 1.5" wheel centric spacers for the rears with extensions built in, plus a set of extended 43mm studs so I can put the spacers that were for the back up front. Then everything should be right. Unless you REALLY know wheels it can always lead to more expense, and even then, like me right now, if your dealing someone who doesn't REALLY know wheels again it will cost you more money than you think. Good luck and keep us posted.

michael

Potomac-Greg

There are SO many ex-Porsche wheels out there that would be better than Chevy wheels. Anything that came off a Cayman/Boxster/928 would work.

Dougs951

A 295 is a pretty easy fit with at most some minor fender rolling

catamax944

You have to machine those 20mm oe spacers to fit the '86 front hubs,ask me how i know. Either that or get a pair of '87 spindles,hubs and discs.

Jfrahm

...but you'd need a spacer and longer studs with these late-offset wheels.

ritzblitz

What are the offsets of the corvette wheels?

Luke714

Once again, I'm so happy to see this is such a friendly and helpful forum. Thanks again guys.

56MM AND 50MM (not 100% sure which is front, I think the front is 56mm)

Some moderate spacers would be fine with me, but I understand the weight issues.

According to this site:

http://www.wheeldynamics.net/appguide.html the extreme fitments are as follows for an 86' 951, do these numbers look about right to you guys?

Does the "et 45mm" mean +45mm offset?

Possible Wheel Choices:

Front
245/40-R17
17x9”
With offsets suggested in the site above, I’m away from my car at the moment so I can’t make measurements. I’m hoping that if I call Wheel Enhancement they can help me out on the offsets. Can anyone recommend someone to buy the adapters and/or spacers?

Rear
295/35-R17
17x11” rims
It doesn’t look like Porsche ever made anything wider than 9” in the 17” diameter, is that correct? Maybe I’ll have to give up trying to use 17” wheels, call me picky I guess. That’s why I thought that the ZR1’s would be good, maybe I’ll have to compromise on section width too?

My conversion so far:

If anyone is interested here are some pictures of the work I've done on my conversion so far. My camera died last August, so I don't really have many pictures of my car since then. The conversion is pretty much completely done now except for some minor tweaks along with wheels/tires and a differential.

• heavier rear torsion bars
• coilovers up front
• adjustable koni's all around
• camber/caster plates
• front strut brace
• SS brake lines
• wilwood manual brake manual master cylinder
• manual steering rack
• 2004 LS1
• 3.5" single exhaust, Flowmaster 40's
• headers with 1.5” primaries and 3” collectors
• 3.5" intake with K&N airfilter
• All aluminum radiator
• solid tranny mount
• tranny brace
• RP fluids all around
• AFR gauge
• aftermarket temp and OP meter
• Spec Kevlar clutch and aluminum flywheel
• External oil cooler
• Corbeau fixed back seats

I did all the machining and fabricating myself, saved a lot of money that way. Below are a couple of pictures. Unfortunately I don’t really have any more recent photos. I can’t believe how amazingly fun this car is to drive now, but it is severely traction limited. Before I get started on ITB’s I want to get the car’s chassis and suspension well tuned.


The 951 and a friends TVR 280i after a drive through the white mountains


Machining the adapter plate between torque tube and bell housing


finished adapter and spacers


coilover kit from ground control 440# springs






New Corbeau Seats, very comfy


Machining the tranny reinforcement plate






plate installed


brace


the new and the old


test fit


best picture I have of the exhaust and oilpan, I couldn't find anyone to do nice bends on the exhaust tubing so I cut and welded. Used a nice Y-pipe though so it all came out really nice.


Griffin Radiator


My version of an engine hoist


Car pre-LS1, a little muddy and sitting pretty high. In the course of the conversion I lowered the car a good 1.5"

xsboost90

Looks pretty good. I ran 295's in the rear w/ some camber and fender rolling- also had 525lb rear springs. I would say 275's fit pretty well w/o having rubbing issues under heavy accel.