Largest tire sizes for track

[racerx]

Looking to see if anyone has experimented with anything bigger than 235/40/18 front and 295/30/18 rear tire sizes. Michelin makes a Pilot Sport Cup in a 265 size, which would likely require a 9" front wheel. Any idea if 9" width, 18" wheels would fit a 99 C2? with some custom offset perhaps? Would a 315 on an 11" width rear fit?

Ran at the track with some Z06s a few weeks ago which were running something like 345 width rubber on all four corners. Needless to say that they were a good bit faster through the corners, not to say it was all tires, but...

Edited December 13, 2006 by racerx

[Loren]

Look at the wheels and tires for a Cup car - those are about as wide as you can go. Some fender rolling and suspension adjustments would be needed to run Cup car widths. Also, don't forget that the more corning force you can achieve - the more oil will slosh into the cylinder heads away from the pickup. Look at the X51 kit parts and or Brey Krause's solutions so that you don't oil starve your engine.

[i300zxtt]

Looking to see if anyone has experimented with anything bigger than 235/40/18 front and 295/30/18 rear tire sizes. Michelin makes a Pilot Sport Cup in a 265 size, which would likely require a 9" front wheel. Any idea if 9" width, 18" wheels would fit a 99 C2? with some custom offset perhaps? Would a 315 on an 11" width rear fit?

Ran at the track with some Z06s a few weeks ago which were running something like 345 width rubber on all four corners. Needless to say that they were a good bit faster through the corners, not to say it was all tires, but...

305's are pretty common with custom wheels like HRE or Iforged. A guy on 6-speed is running 315's in the back on 19x11's. You need custom wheels, rolled fenders and run extreme camber. Also, the GT3's on cargraphics website say they are running 315 tires as well...

Cup car is running (27/68-18) tires in the back.....I have no idea how to convert that into street msmt.

Edited December 14, 2006 by i300zxtt

[racerx]

Look at the wheels and tires for a Cup car - those are about as wide as you can go. Some fender rolling and suspension adjustments would be needed to run Cup car widths. Also, don't forget that the more corning force you can achieve - the more oil will slosh into the cylinder heads away from the pickup. Look at the X51 kit parts and or Brey Krause's solutions so that you don't oil starve your engine.

Good advice as always Loren.

The Porsche Manufacturer's Cup sizing looks to be:

Front axle

• Three-piece BBS light aluminium rims (9J x 18), rim offset 46 with central locking wheel nuts

• Michelin rain tyres (24/64-18)

Rear axle

• Three-piece BBS light aluminium rims (11J x 18), rim offset 59 with central locking

wheel nuts

• Michelin rain tyres (27/68-18)

But maybe some room for more with a few tweaks:

Here's the description from a cup car for sale: 1999 Porsche GT3 Cup (with factory airjacks and ABS) 2002 Kelly-Moss racing updated to RS spec (460HP motor, Wing Body, 3 Way Moton, 12" rear rim x 10.5" from rim)