Experience with various widths of D90's

[spacecad3t]

I recently picked up a front pair of D90's to complete a set. They were on a 944, but what I didn't know at the time was the 944's came with 7" fronts and these are 6" fronts, which from my research, came on the 911?

I then saw a post on Instagram about "Double D's" being 8" D90's in all 4 corners.

Now, I get where in a straight line, four 8" wheels with proper tires would be very nice grip, but to me, 8" in the front doesn't sound ideal for cornering... However, I can see how 6" could cause understeer.

Questions:
- Anyone have any experience running combinations of 6" / 8" wheels? Notice anything?
- Is the understeer real? I feel like this could dialed out with tire choice and alignment?
- Should I be looking for 7" fronts? (This would be annoying lol).

My gut says proper tires on the 6" wheels with alignment adjustments would actually be ideal for cornering capability, but I don't have any experience racing with the 944 yet.

[944er]

I don't believe there was an 8x8 fitting on any 944 from the factory outside of racing applications. 7x8 on turbos, 7x7 on NA cars. There are 5.5 and 6 inch rim fittings for snow tires though.

[spacecad3t]

I don't believe there was an 8x8 fitting on any 944 from the factory outside of racing applications. 7x8 on turbos, 7x7 on NA cars. There are 5.5 and 6 inch rim fittings for snow tires though.

Yeah thats true. The 8x8 is a custom setup people create from 2 pairs of 8" wheels. I didn't come across that configuration from Porsche.

[walfreyydo]

The 944s (and most factory configurations on most cars) were setup to understeer from the factory. The 7" wheels that came on the fronts of most 944s I think were part of that design.

Moving to an 8" front wheel (otherwise referred to as a 'square' setup with two sets of rear oem wheels) will help with understeer and move the car towards a more balanced feel, which will help it be quicker in autox and on the track. When I bought my car it had this exact 8" square setup with a set of rear D90 wheels. During autox events I think the car handled better with less understeer, than the times when I ran a 7" front wheel.

On the street, you wont really notice, so theres no real reason to run an 8 over a 7 under street conditions, and from a safety standpoint, running a 7 is probably a bit safer (to inhibit oversteer in emergency situations). A 6" wheel I am not so sure I would run. It was not designed for a Front engine rear wheel drive car, it was designed for a rear engine 911, and the car will understeer even more. I also dont like it from an aesthetic perspective (ie: skinny pizza cutter wheels), although that is subjective I guess.

I am now running a 9" square setup on a set of early offset phone dials (which I sent out to be widened) and the car has even more grip and feels well balanced between over and understeer. I also felt like my car was much faster when it was setup with more oversteer, it rotated better and faster through corners (not to mention more fun having the rear end swing out more). I am not a competitive autox'r so not really speaking from a position of expertise or anything, I just enjoy tinkering, testing and working on my car and driving skills and these are some of the things I have noticed and learned.. There are many other factors that will influence the handling of the car such as F/R tire pressure, spring rates, alignment, LSD/TBD and sway bar config among others.

Again, I think the differences between 7 and 8" fronts are really only felt under performance driving circumstances and are less of a concern on the street, although I would not run a 6" front wheel personally under either circumstance.


9" square setup with Toyo Proxes RA1 245/45/16 tires

[spacecad3t]

Thanks a ton for that response!