What size tyres

[Andy Sykes]

Hi I'm about to order some new wheels for my race car whats the largest tyre you can fit  under a standard rear wing the car is IRS 1" narrowed

Cheers andy

[Fasterbrit]

There won't be a definitive answer really as there are so many variables including ride height, wheel offset and type of spring plate used etc. On my old Oval which had stock wings, one inch narrowed IRS and six inch Ercos I could run 205 width radials and six inch slicks. I had stock inner wings, which were the main limiting factor. It's pretty much a case of trying and seeing what fits. Can you borrow a wheel and tyre combo or two? That would help a great deal

In contrast All Torque has stock wings, no inner wings, a five inch narrowed IRS and eight inch Ercos and I can squeeze 8.5 inch slicks under the wing. Hope this is of some use

[Andy Sykes]

Cheers Mat thanks I have 6" Eros at the moment and they fit fine I'm may to cut out the inner wings as they don't do much now I guess I better get my measuring tape out tmw, I'm not sure how big I need to go to get the power down I'm planning on about 600 ish bhp but who knows until the engine is done a set up

Cheers andy

[Fasterbrit]

You will need an eight inch slick and seven inch rim minimum. Don't try to fit an 8 inch slick on a six inch rim as it will 'belly out' giving
You a much narrower tyre contact patch. I found that out to my own cost...  For the road a 225 tyre such as Toyo Proxis will give you a bit of grip. Not much though, if you turn up the boost! 
Hoosier street treads will give you good launch traction, but no stability thru corners... You can't have it all  sadly

[Andy Sykes]

Ok thanks I will have a measure up tmw if I have to put wide wings on I'm not too fussed rear end is like this



Cheers andy

 

[Carsten]

Have the same , 69 with IRS.
Hade different wheels on it , but the original steel wings were a little widened (hope that is the right word).
7x15 ET 23 with 225/60/15 or 26x8,5x15 slicks or 6x15 Fuchs with 235/60/15 MuH or on 7x15 ET42 Fuchs with 5mm or 20mm spacers (both were possible) or 7x15 ET 13 Weld Racing draglite with 205/70/15
Alle the rims above were possible with the 205/70/15 and were tested with them on the car.
16" inch wheels had 225/45/16 or with NITTO DOT slicks 225/50/16.
Car is about 1,5" to 2" lower in the rear. Will try to post pictures. Or can send you if you like.
Hope it can help you and sorry for giving ET not rearspacing .
Greets , Carsten

[Carsten]

Have the same , 69 with IRS.
Hade different wheels on it , but the original steel wings were a little widened (hope that is the right word).
7x15 ET 23 with 225/60/15 or 26x8,5x15 slicks or 6x15 Fuchs with 235/60/15 MuH or on 7x15 ET42 Fuchs with 5mm or 20mm spacers (both were possible) or 7x15 ET 13 Weld Racing draglite with 205/70/15
Alle the rims above were possible with the 205/70/15 and were tested with them on the car.
16" inch wheels had 225/45/16 or with NITTO DOT slicks 225/50/16.
Car is about 1,5" to 2" lower in the rear. Will try to post pictures. Or can send you if you like.
Hope it can help you and sorry for giving ET not rearspacing .
Greets , Carsten

Slicks


225/60/15 on 7x15 ET23 Porsche

236/60/15 M&H on Fuchs 7x15 ET 42 with 20mm spacer

[Carsten]

Some more pics: