Max wheel size 964 C4

[joetiii]

How large wheels can be fitted on a stock 964 C4, both diameter and width?

thanx

[rbogh901]

see Bill V's sticky. it's a real resource. tire sizes, wheels, etc. let us know what you end up with.

[rbogh901]

"964 front can use from 6x16 w/ to 8x18 wheels w/ 225/40 to 235/40 tires, though the latter get very tight, the lower the car the tighter it gets oem RS came w/ 7.5x17ET55 & 205/50x17 tires

964 rear can use from 7x16 to 10x18 w/ 265/35 tires though again the rear is very tight, largest factory fitment was 9.5x18 on n/b and 10x18 on w/b. oem RS came w/ 9x17ET55 & 255/40x17"


- per Bill's data


__________________

[joetiii]

Gotta find Bill's sticky.

I wanna get some older style fuchs with polished petals to fit.

I saw a C2 with some jeff Altons. Nice looking but kinda spendy. Linea Corse makes some I think and stock size is OK.

[jpachard]

I've got 235/ 40 front and 265/35 rear Pilot Sport Cups(18's). Really, anything larger on a narrow body car is over-tiring the car and slowing it down.

James

[rbogh901]

Same here even though Porsche doesn't recommend 18's on the 964's. Fit is fine. James: What rims/offsets/ride height do you have?

Joe, it's at the top of this forum, "993 vs 964 systems analysis" or something.

[jpachard]

Everyone I know who Club Races these cars runs 18's without issue. I have BBS LM's 8F 9.5R and a very low ride height( I don't have the exact number. I'm running RSR shocks with 600lb front and 800lb rear springs.

[911st]

What is the rear tire limit?

265?

[jpachard]

I've seen guys shove in a 285 hoosier....

[SAM DACOSTA]

Although Porsche doesn't recommend it. I run 18's on the street and then 17's on the track. Here's a C2 with 225/40 (F) and 255/40 (R) running 18's.

[jpachard]

I just put 265/35R and 235/F Michelin Pilot Sport Cups on with out issue. I did have to put a 6mm wheel spacer in on the passenger side rear though.

[zero26]

so it is impossible to fit 18x8.5 ET 54 and 18x10 ET 61 to 964 C4? because i am thinking ordering a set of wheel for my 964 but would like switch it to my 993 sometimes

Thanks
Albert

[Bill Verburg]

You need to consider all the various parameters when up-sizing wheels and tires the closer to max you get the less wiggle room there will be

James setup is a great no-brainer that was used on the factory 964 Cup cars. Factory used both 17 and 18 but the wheel width and ET was the same for both
8ET52
9.5ET68 used w/ a 21mm spacer for a net ET47
235/40 and 265/35 at 25.4" & 25.2" tall are a good match for tires being close to the same height which aids ABS function and not too tall which aids acceleration.

This car(a very successful club racer) uses 993 8ET50 and 10 ET65 x18 w/ spacers in back(unfortunately I don't know the spacer size but they look to be ~21mm for a net 10ET44, Tires are 245/35@24.7" and 275/35@25.5"







others have reported using
8.5x17ET51 & 10x17ET44(or 9.5ET51)
8.5x18ET50 and 10x18ET44 w/ 245/34 & 285/30 tires
8.5 x18ET56 w/ 245/35 & 10x18ET65 w/21mm spacer 285/30

[zero26]

Thanks Bill

[Faster993]

Bumping this thread for some help and advice.

My 1990 C2 is currently running on BBS wheels 8” wide up front (not 8.5”) and 10” rear. The offsets are 49 front and rear. The car is used primarily for the track. I’ve been running on 265’s in back, and 225’s up front. The car is nicely balanced, but it pushes just a bit up front.

I was thinking about increasing to 285/30 in the rear, and 245/40 up front. The 285 is doable with 10mm spacers, but there’s no way I can fit 245’s up front without new front wheels with 40ET offset. My front end has 993 longitudes and BBI wheel carriers, so that might explain why it wants 40 ET offset. Im not planning on replacing the wheels just yet.

So, the question is does it make sense to move to 285/30 in back and 235/40 up front? Will this create more push up front? I’m willing to experiment for a season to give it a try, but welcome any feedback from the Forum, and of course the experts like Bill V.

[Bill Verburg]

Originally Posted by Faster993

Bumping this thread for some help and advice.

My 1990 C2 is currently running on BBS wheels 8” wide up front (not 8.5”) and 10” rear. The offsets are 49 front and rear. The car is used primarily for the track. I’ve been running on 265’s in back, and 225’s up front. The car is nicely balanced, but it pushes just a bit up front.

I was thinking about increasing to 285/30 in the rear, and 245/40 up front. The 285 is doable with 10mm spacers, but there’s no way I can fit 245’s up front without new front wheels with 40ET offset. My front end has 993 longitudes and BBI wheel carriers, so that might explain why it wants 40 ET offset. Im not planning on replacing the wheels just yet.

So, the question is does it make sense to move to 285/30 in back and 235/40 up front? Will this create more push up front? I’m willing to experiment for a season to give it a try, but welcome any feedback from the Forum, and of course the experts like Bill V.

Lots of stuff that doesn't make sense here
993 long. on a 964 will push the A-arm out 12.5mm, Hopefully some additional compensation is done at the shock top w/ the hats to get reasonable camber

it's common for 993 to have 964 to pull the wheel back into the body to allow a wider front wheel, 993 Cup and RSR did just that, don't see the point of 993 long on a 964 unless you use turbo flairs and then don't want to go to the outer mounting holes


an 8ET50 is a normal 964 front fitment but if the wheel has been moved out by over 10mm the ET should also need adjustment back in board to ~59

not sure that a 285 will fit in the back, widest I've ever seen fitted is 275 and that was extremely tight on both sides that is w/ a 10 ET45-50

if the car is pushing one remedy is a wider front 245/35 x18 on an 8.5 ET 40-48 is common w/ the 275/35 rear

be very careful of a 245/40 front it is just way too tall for a comfortable fit