Need help clearancing for 28" tires

[Jim S. '95 Z28]

Just mounted the 28x10x16 Hoosiers on stock wheels and the clearance seems a bit tight. There is 1" of space between the tire and rocker panel in front of the tire, and about 1/2" between the bumper and rear of the tire. Is this enough clearance for the tire as it expands down the course of the track?

If not, cutting out a portion of the plastic rear bumper wouldn't be too difficult. As for the rocker panel sheet metal, would it be best to hammer, cut, or both? Any pictures, tips, or recommended tools is greatly appreciated!

Fortunately, clearance between the wheel well lip and top of the tires is beatiful!

TIA!

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The Toy
The Commuter
"Real men drive opposite lock."

[This message has been edited by Jim S. '95 Z28 (edited July 25, 2002).]

[TedH]

I used a hacksaw for my 28" x 15" x 12.5" ET Streets, but only on the rear sides. I had to trim back the plastic and the metal indside. The side behind the door had enough clearance. It was a real "hack" job as time trials were starting in less than 1/2 hour when I tried to put the tires/rims on the car. I'm sure there is a better way to do it than I did.

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'94 Black Z28, 383, 700R4
1/8 ET: 7.49
1/4 ET: 11.86
1/4 MPH: 112
http://www.downtime.cz28.com.index.html

[Jim S. '95 Z28]

Ted,

Should 1" of clearance be enough for the space between the front of the tire and rocker panel (area behind the door)? How much clearance is there in that spot with your MT's?

[Injuneer]

When I put the Hoosier QTP 28x11.5-15's on, there was a shade less than 3/4" in front and a little less than 3/4" in back of the tire. I started to see signs of the tire contacting the front edge/sheetmetal when trap speeds got over 120-125mph. How the QTP's compare with the 28x10-16 slicks is unknown, but they both show as an exact 28.0" diameter in the catalog.

My solution was to move the axle back about 1/4" to give closer to 1" in the front and a tight 1/2" in the rear, so that any contact would by with the softer plastic. When that happens, you will very quickly find the tire will "radius" the bumper cover. I've seen it happen on a friend's car. Just don't let it get too far into the plastic, since there is a metal reinforcement a little behind the plastic.

I also gently "rounded off" any sharp edges on the quarter panel with a hammer, just in case.

This is the way they sit now:

http://cjcfo.fbody.com/members/injun.../DCP02912a.jpg

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Fred
94 Formula A3: 381/TH400/N2O

Advanced Tech Posting Guidelines
Detailed Mod's List
11.513@115.59 on motor; 11.162@127.67, 1.643 60' on a 125-shot. Going with a 275-shot this year


[This message has been edited by Injuneer 94FormM6 (edited July 25, 2002).]

[Jim S. '95 Z28]

Fred and Ted,

Thanks for the tips. VERY helpful as always, especially the pic! Thanks for taking the time to snap a shot Time to bust out the hacksaw and hammer and have at it

[This message has been edited by Jim S. '95 Z28 (edited July 25, 2002).]

[TedH]

How much clearance you need will be determined by the speed you are going at the top end and the actual diameter of the tire and how much it grows...

I'm only trapping between 110-112 on a normal day so I don't need as much clearance as someone trapping 125. I have about an inch and its no problem for me.

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'94 Black Z28, 383, 700R4
1/8 ET: 7.49
1/4 ET: 11.86
1/4 MPH: 112
http://www.downtime.cz28.com.index.html

[CANTONRACER]

Maybe you should call the tire manufacturer? I bet they know, or at least I hope so.

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1996 Z28 Camaro
2001 best 1/4 BFG DR's NA - 11.865@113.57 w/1.634 60', 1/8 - 7.563@89.82mph Best 1/4 MPH 114.82 - Best 1/8 MPH 90.73 - 2002 Mid 11's NA, Mid 10's n2o

1989 GMC 1500 truck for work 18.1@73 305
8 cats to feed clean after 1999 V6 Mustang 5 speed
15.358@89.47 MPH w/ 2.227 60'
15.364@90.92 MPH w/ 2.383 60'

[Jim S. '95 Z28]

<font face="Verdana, Arial" size="2">Originally posted by Raptor1:
LMAO, I'm afraid that would be a false hope </font>

LOL

Just got off the phone with them and tire growth shouldn't be much of an issue with projected low 120ish traps. Gonna massage the "problem areas" just in case.


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The Toy
The Commuter
"Real men drive opposite lock."