horst

My car is a 90 C4 with bone stock suspension. I have a set of after market cups, 17", F= 7-1/2, 52 mm offset, R= 9, 47 mm offset. I would like to mount Kuhmo Ecsta MX F=225-45-17, R=255-40-17, but am worried about the possibility of rub at the front. Has anyone tried this? Opinions solicited.

My other option, it seems is to go to 205's in the front.

Need new tires asap, as several driving events are looming.
TIA

Adrian

Dear Horst,
I use a 5 mm spacer up front for the 225s just to be safe. I use Toyo T1S 225/45ZR17s on 55 mm ET wheels. You might just get away with it with 52 mm ET wheels.
Ciao,
Adrian
911C4

Jeff Curtis

Horst, without the right steering stops you WILL have rubbing, it's just too darned risky to mount 225s up there. When you rode with me at Beaver Run, I have my street 215s on there, they are 2mm "shorter" in profile, so you can imagine there's NO negative effect.

The people that would argue that are out of their mind.

Adrian uses 5mm spacers with 55mm ET wheels, so that's effectively 50mm ET...but I would imagine he has 7" wheels??

With your 52mm ET wheels, 5mm would put your tires into your fenderlips for sure...even with 3mm you would be out there...remember, that 1/2" you have over 7" is an additional 12.7MM!! <img border="0" title="" alt="[Eek!]" src="eek.gif" />

I would go with a 215 series tire and call it a day, no rubbing no worries.

Mine do not rub, but I do run a 3mm spacer up there with a 55mm ET wheel that is 17" x 7". My 225 series track tires DO rub the inner fenderwells.

I imagine I could put 5-6mm worth of spacing up there, but it would be unsafe for track use without longer wheelstuds. I have the proper steering stops...just have to find the time to install them in the midst of cutting/grinding/sanding/wire-wheeling/priming and taking things apart!! <img border="0" alt="[grrrrrrr]" title="" src="graemlins/cussing.gif" />

SO, I think once I get the 10mm steering stops installed, all my rubbing woes will be put to bed.

BTW, I use the Bridgestone Potenza RE 730s, which are a relatively "skinny" tire compared to other manufacturer's tire widths, some 215s are actually 5mm wider than MY 215s!!

Check it out yourself at <a href="http://www.tirerack.com" target="_blank">www.tirerack.com</a> - pick the tire you're interested in and checkout the specs when mounted on your particular wheelsize...you'll be amazed at the difference.

BrokeAss

Horst - I can't add anything more to Adrian or Jeff's comments other than my personal experiences. I've got a C4 with the same tire & wheel sizes as you and have the steering stops installed. With my lowered suspension I was able to get a bit of rub with the suspension fully compressed at a recent autocross. After that 'unpleasent' experience, I'm having spacers installed this week.

Adrian

Dear Horst,
I did not notice you are running 7.5Jx17. I would not install these onto a C4 anyway. They are too wide for a 1990 model and I agree with Jeff. You will need the 10 mm steering stps (you have 6mm fitted) and you will also need spacers if you run 225s. You will also reduce your steering lock. Actually I think you will get rub on the inside almost for sure. For the record my 225s do not rub at all with the 5 mm spacers fitted. I am lowered to RS specs though and ride height makes a difference. You can be too high or too low. 3 mm can make a difference. I helped a RSA owner with a similar issue and we raised the front by 3 mm and the rubbing was fixed.
Ciao,
Adrian
911C4

horst

Thanks. I have changed my order, based on your guidence. I have 215-45-17 & 255-40-17s Kuhmo Ecsta MX tires coming. I said I have a "bone stock" suspension, that is not 100% true; I just remembered I have installed the 21mm rear sway bar. Now with the wider tire up front this may further reduce understeer (?) Any suggestions as to tire pressures?

Jeff Curtis

I run my pressures at 34-36F and 38R...just something I tried shortly after purchasing the car as I didn't believe the 38F 42R (I am going from memory, may have quoted that incorrectly) that the factory suggested.

Horst, NO spacers and the 215s should work fine, this would be essentially the same setup I use as I have 55mm ET with 3mm spacers, that makes it 52mm and your wheels are 52mm ET. You do have a wider wheel though, it should all go to the outside.

Try this, I'm thinking it will work well, I know C2s and C4s can have 7.5" wheels, it's been done.

horst

Will let you know how it all works out in a couple of days