Wide Tires on an '83 SC

Andras Nagy · 01-17-2005, 06:24 AM

Now I have another dilemma.

Having borrowed a friend's Toyo RA-1 tires to see if they fit under my car, here are the facts and my question:

1. Toyo tires borrowed are 225/16 fronts, 245/16 Rears, mounted on 7's and 8's Fuchs.

2. My car is lowered to Euro specs (see Bruce Anderson's book). I had rolled the fender lips 20 years ago.

3. My "normal" track tires are 205/15 on 7s, and 225/15 on 8's (for lower gearing on the usual tracks), mounted on BBS wheels.

4. These much wider borrowed tires fit under my wheel wells, and I have driven them on the street. There are appreciable gaps on both front and rear fenders. During street driving, there was no rubbing, not even at full steering lock, left or right.

Now the question: has anyone ever run these sizes on a lowered 911 SC, and is there any rubbing under track loading-up of the suspension?

I would like to buy these tires, but am worried that they will rub when the suspension get loaded up on sweeping left or right "carousels", aor when running on the curbs, or perhaps even when the track dips and the car get down-loaded and then "pogos" for one cycle.

Other than taking them on the track and seeing for myself (he is willing to let me do this, but we'll have to wait until the next DE to do so), is there a way to "test" the clearance?

Thanks for your experience.

IROC · IROC's Garage

There isn't any reason why they shouldn't fit fine. Many people are running much larger without rubbing problems. I have 245/45s and 275/40s front/rear on my '76 with SC flares, for instance.

Mike

rdane · rdane's Garage

I agree with Mike they should be fine. But you also may have to renew your suspenion if the car rubs under hard driving conditions.

Mike would you please give us the details on your 245/275 set up? Rim size, tire brand and anything you did to get them under the car would be great.

IROC · IROC's Garage

Quote:

Originally posted by rdane

Mike would you please give us the details on your 245/275 set up? Rim size, tire brand and anything you did to get them under the car would be great.

Sure. I'm using 8x16 and 9x17 HRE Fuchs replicas. The fronts have a 5.75 inch backspacing and the rears are the standard "930" backspacing (5.5"?) for 9 inch wheels. I have used both the old BFG R1s and Yoko A032Rs without any problems. Rolled fender lips front and rear, about 1.5 degrees of negative camber and 22/29 torsion bars and everything seems to work fine.

I've been using this set-up since 1997. Needless to say, I have plenty of tire for a 2400lb car.

Mike

rdane · rdane's Garage

Thanks Mike. Where are you getting the Yoko 275s?

IROC · IROC's Garage

The last set I bought I got from the Tire Rack.

Mike

Andras Nagy · 01-17-2005, 10:37 AM

Getting back to the original topic at the top of the BBS, anyone have any concerns that these much wider tires that my stock ones will give me trouble on the Track.

Any experiences, both positive or negative?

JeremyD · JeremyD's Garage

At euro settings you should be fine. These are the same size tires I run at Sebring - and I have 951 8's which push out the fronts a little further. With 7's you should be fine -

Andras Nagy · 01-17-2005, 12:11 PM

Thanks Jeremy,

I'll try them out some on the street and I-95, which has some nice dipsy-doodles, which ought to unload the suspension, and then load it again.

By the way, when can I sign up for Suncoast Region's single-day DE event at Sebring? Is it supposed to be in March or May? Your WebSite doesn't yet show it on your calendar, but our Local Newsletter shows it for May 28.

There, I've done it - I highjacked my own thread!!!!!!!!!!!

JeremyD · JeremyD's Garage

The only issues I have had are the fronts - usually the driver's side as far as rubbing goes. Try to find a drive way with a steep angle and go up a little faster than normal. you'll find if you have rubbbing issues pretty quickly.

This is what I have (from a pretty good authority) as the Suncoast DE days...

March 26, Saturday, Short Course
June 18, Saturday, Full Course
September 24, Saturday, Full Course
November 12-13 Sat-Sun, Full Course INSTRUCTORS WEEKEND

Andras Nagy · 01-17-2005, 01:06 PM

Thanks for the dates Jeremy,

However, when I go to Suncoast Region's WebSite, they don't have these dates on their Calendar, and there is no one listed to contact to register.

Do you have an e.mail address for someone who might be able to register me?

JeremyD · JeremyD's Garage

They are a little antiquated -

I'd download the .pdf file, then send it in with a check...

http://www.pca.org/sfl/drivers_ed.htm

Walko · Walko's Garage

Andras,

I was running 245/45/17 and 265/40/17 on my 75 911 with SC flares. as well as 245/620/17 and 265/620/17 slicks

Rubbing on the right rear guard was a problem in that I was now had so much extra grip that i could load up during a corner and burn the underside of teh guard causing eh paint to blister on the outside.

The suspension setup was very stiff and no matter how much i increased the spring rate the same problem occurred.

Predominatly this problem occurred on longer races and most of teh photos that depict this problem also show the front opposite side wheel off the ground.

Attached picture so you can see the wheel lift.

Michael

IROC · IROC's Garage

Quote:

Originally posted by Andras Nagy
Getting back to the original topic at the top of the BBS, anyone have any concerns that these much wider tires that my stock ones will give me trouble on the Track.

Any experiences, both positive or negative?

Andras,

My car - with the 245/275 tire combo - has spent quite a bit of time on the track and I haven't had any problems. You should be fine.

Mike

Andras Nagy · 01-18-2005, 03:28 AM

Thanks Michael,

That's the kind of information I was looking for - real-world experience.

Now, with the possiblities of 225/16 in front and 245/16 in the rear, perhaps I won't have the same wheel burning issues, since your extra 20 mm is probably what caused your burning. For the moment, I'll still try some dipe on the highway, and see what happens when the car loads up and then unloads, and loads up again. Still no indication as to what may happen on the track, but the seller is going to allow me to use the tire combo on the track, so we'll see.

Thanks again guys.

rdane · rdane's Garage

I am Euro ride height on my SC. I have rolled the fenders and run any of the following combos with no issues: 7 and 9 16" Fuchs 225/245, 8 and 9.5 16 Fuchs, 225 and 265 and 8 and 9 17" Fikse with 235/255.

On my car the 7 and 9 930 Fuchs have a lot of clearence running 225 and 245 tires as long as they are only 25" tall.

Walko · Walko's Garage

Andras,

I don't think it is always the width of the tyre which causes the burning issue/ rubbing on the underside of the guard but rather how hard you push your car. I know people who have never had teh problem with the same type of car and tyre setup. I must admit they never got close to my lap times either.

My two cents worth.

I suppose it all boils down to how hard your suspension is.

Michael

rdane · rdane's Garage

I agree with Micheal. When pushing tire size suspension plays a roll. I am running 22/20 sway bars, 22/30 torsion bars and custom valved sport bilstien shocks.

Walko · Walko's Garage

Rdane hith the nail

I was running 23/32 t Bars and 20/21 Sway bars
The front shocks bistein revalved and the rear Bilsteins with coilovers and 220lbs springs.

Michael

Andras Nagy · 01-19-2005, 03:29 AM

Then I guess I should be okay, since I have a rock-hard suspension as well as the Euro-lowered height. You can't even budge the fenders when pushed down, and yet when I run street tires (Continental Tourings) on my normal Fuchs, there is sufficient compliance in the tires to offset the stiff suspension. Best of both worlds.

Thanks guys, I'll try my combo on the track and report back.