Marc Shaw

Okay Keith, thanks.

I'll give the spacers a try but I suspect a JIC suspension is in my future too......darn!

Marc

kgorman

Sorry to weigh in so late Marc. I had the exact same problem with MPSC 255's and H&R Green/Bilstien and RS alignment. I tried everything, and finally ended up with 8mm worth of spacer on ET55 CUPII's ~ET47. Even then I got some rubbing. Somewhere around ET47/48 is the sweet spot I think. So for you, probably a 3mm spacer.

The final fix. JIC-Cross suspension. Since then, no problems at all, and I have even gone to 10" rears!

RSAErick

Hi Marc,

I couldn't remember what size I ended up with, so I just went out and pulled a wheel off to measure. It looks like I settled for a 6mm spacer. It did the trick, although with rolled fenders, there's plenty of room for more. FYI, I've got a rather soft suspension setup - H&R coilovers.

Interesting that it seems to be the MPSC's that have this problem. I suspect that they are sized wider than advertised. I initially considered the Toyo RA-1's, but several years ago the difference in radius between the front to rear widths were greater than 6%. Porsche specifies that the radius difference between front to rear not exceed 6% for ABS purposes. Maybe they've added or changed sizes?

Anyway, best of luck. Let us know how the spacers work. If you "need" the JIC suspension to solve your problem, I'll be anxious to hear how it works. I am considering the same.

Marc Shaw

I have to admit that I'd be suprised if just a 3 mm spacer is enough looking at how large the rubber smear was so how much tire contacted (I'll post a picture once I pull the wheel off later this week).

I have a 7 mm spacer with longer studs already so I'll try that but I'm sure a fender rolling will be needed to fit a spacer that large -- that would make me at ET 43 so pretty close the the minimum 44 that seems to crop up.

Yeah, I'm already pricing JIC.....

Marc

Chris M.

Any updates Marc? Did you do the spacer/lug install yet?
I discovered this when I switched my MPSCs out after Mid Ohio last weekend. I've had rubbing before but never this bad and never on my cat heat shield. I just had an alignment too. Hmmm...?

bjorne

Hi, also curious what the final outcome was, I just bought a spare set of track wheels, the rear is 8.5x17 et 50, with mich cup tires, car is a 94 964 with JIC susp, wondering if I will be O.K., I know there is no rubbing with the stock 8 inch rears et55, cup tires,
Thanks

Marc Shaw

I had a set of 7 mm spacers from H&R with the "longer studs" but it turned out the studs in the box were standard 45 mm studs.

I have since ordered 52 mm studs as well as a set of 3 mm spacers (so I have 3 mm, 6 mm, and 7 mm spacers to play with). The studs shipped 3 days ago so I am hoping they show up early next week. The car is up on my new AC axle stands waiting for the studs to arrive and then I have a track day June 25 where I can push the car in the corners and see if it still rubs.

When I took the front wheels off, I noticed a lot of rub with the right front tire too so I am planning to put longer studs and a spacer in front too.

Marc

Marc Shaw

I took a few pictures after work today.

Marc

Tom W

I'm late to this thread because it started while I was in Bora Bora on vacation...

Marc: You need a spacer. Mine are 4-8 mm range, I can't remember which. I had bigger studs added. (I have the JIC suspension but it had no impact on the rub without spacers or with smaller spacers when running MPSCs).

The stuff on the front of the arm like in the photo Chris posted can come from the rubber wearing off the tire and then the stuff that's destined to become 'marbles' rubbing off on the arm. That's not a problem, my car does it all the time. I have marked the inner edge of my tires (grease pen but shoe polish works too) to show that it's not coming from the inner edge of the tire.

Chris M.

Tom have you installed stiffer control arm bushings?

ThomasC2

R-tyres are stiff and I’ve heard that because they are so stiff they kind of tilt sideways under load instead of being compressed, and that the Michelin Cup tyre has very stiff side walls compared to others. This could therefore be the reason why people get more rubbing from this tire compared to other R-tyres. In other words, the tire under load is “leaning” inwards and leaving rubber, it’s not rubbing all the time. I don’t have any rubbing with my Toyo R888’s but I do with my Cup-tires. Just a thing I’ve heard…and probably are spacers the only solution if you can’t live with it. But it was also an interesting test you did Tom that showed that it’s probably just old rubber scarping of.

roger zimmerman

I never had this problem on my RSA with Bilsteins/red H&R springs. Tires were 255-40-17 Toyos RA1s and Yoko 032s on 9" Kinesis Supercups. This year I went to 275-40-17 Avons and I had to install 8mm spacers just to clear the oil line at static setting. On the track I got a slight polishing in the same spots but it didn't even mark the tire and didn't happen again at the next event. The 275s are a very tight fit and might not be worth the time to make them fit. I suspect that it also kills acceleration but am faster than last year so I guess thats what counts. Fitting tires/wheels on our cars seems to be a more difficult project than most expect because what fits on one car won't fit on another. In other words listen to the general rules but check your clearances carefully before running your car.

Marc Shaw

I had another go at the track with 52 mm studs and a 6.5 mm spacer and I had a small amount of rubbing still but only on the oil line - none anywhere else.

I have now swapped in some 56 mm studs and put in a 8 mm spacer which may be pushing the limits with the rim having an ET of 50 so I may need some tire rolling to prevent fender rub.

I'll report back after my next track day.

Marc

garrett376

Get some new tires!!!!!!!!! Toyos!!!!

Marc Shaw

Umm...I just dropped almost $2k on MPSC's so I have to wear them out first.

Marc