How much clearance is needed between the tire and the outer wheel wells?

I am currently running 26 x 10.5 x 15 ET Streets with a 26.1" diameter and have 2.19" clearance in the front and 1.81" clearance in the back. Going to 28" slicks (28.1" diameter) I will have 1.19" in the front and only 0.81" (13/16") in the back.

Is 13/16" enough clearance? How much distortion occurs during launch? How much growth at top end (118 mph)?

How much clearance do you guys have (injuneer?)?

If 13/16" is not enough, how do you gain clearance? The front is metal but the back is molded plastic.

 

I ran the Hoosier QTP 28x11.5-15's (no tubes), listed at 28.0" and they fit fine, and rubbed on nothing (the inside fenders had previously been hammerd for 315's), until trap speeds reached ~125MPH. Then the tires grew enough that they were rubbing in the metal fender at the front of the wheel opening. I moved the axle back about 1/4" and that solved the problem.

Later switched to ET Drag 28x10.5-15W (with tubes), listed at 28.1". They would not even fit past the lower point of the rear fender bumper cover (remember.... my Firebird has a different fender line than your Camaro). I had to start cutting the leading edge of the bumper cover back to the point where is had maybe 3/4" clearance, just about where the sheet metal behind the bumper was located - I actually hammered the tip of the sheet metal down a bit. I'm not sure why the ET Drags were so large in diameter, and I'm wondering it running tubes had something to do with it????

Doing some dyno testing, we took it up to about 130MPH on the chassis dyno, and the slicks grew enough that there was a groove in the tread, indicating it had made contact with the tip of the sheet metal. I hammered the sheet metal back even more, and cut at least another 1/2" off the leading edge of the bumper cover. I haven't run the car in a couple years, so I'm not sure if this worked.

I have some pictures of the tire/fender clearance. I'll post them tomorrow. I may actually have the link in my FAQ writeup... can't remember. I'd go out and measure it, but I have my street tires on the car right now.

 

Thanks, I'd like to see the pics.

 

I think camaros are less of a problem. I have MT 28-10.50 and they never rubed in the front.....they rubbed the bumper cover a little in the rear and I had to adjust my control arms forward a little. I cut out the bumpstops etc. and did a little work on the inside wells a long time ago....My biggest problem was locating the rear....it would rub one side when I launched...with a spohn drag bar and stiffening the shoks it took care of it. Before I was leaning to one side during the launch..

 

These were taken when the bumper was cut just about enough to fit the tire in the opening:





With the full cut on the rear bumper:

 

Wow, that was really tight before you cut the bumper.

You did an amazing job cutting the bumper. You can't even tell from the side shot.

Thanks for taking the time to post the pics, it was a big help.