askulte

Hey guys,
I think its about time I stepped up to the plate with the big boys, so I'd like to get some drag wheels and tires. I put together a spreadsheet for figuring out trap speed vs diameter/rpm. Staying in 4th gear (on a T56) with 4.11's, a 28" tire will get me 121 mph at 6000 rpms. Will a 28x12.5x15 fit in the stock fender opening? I don't know the width at the sidewall bulge. If not, what size should I go with? TIA!



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Andris Skulte
Skulte Performance Designs
Z28tt-89 IROC T56 DFI Twin Turbo
http://www.skulte.com

NJ SPEEDER

i have seen people with 30in tall tires on thirdgens before, so the 28's shuoldn't be a problem. i can't say i remember anyone ging 12.5 wide though. i know there is a guy at e-town all the time that runs an 11.5, but that's the biggest i can remember seeing.

lata
tim

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91 Camaro RS-LO3,Auto.
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Formula-91

I'm running 27.5 x 11.5 but I've got the wrong backspacing. I've got about 1.5" sticking out on either side. If I has a 5.5" backspace instead of 4.75", they would fit fine.

ethan71

I used to have 275/60s, but they did rub, they were 28" tall but 11 inches wide. When I cornered fast (about 60mph in a 90 degree turn) it rubbed pretty bad, also the traction was better either, only in straight line racing. The biggest without spacers would be about 255/60s on stock rims.

Ethan


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'88 T/A
305 TBI with WC-T5
50,000 miles
Flowmaster 3" exhaust
14" K&N Open Element

AlkyIROC

I have 15x10 rims with 5.5 backspace. My current tires are 28x9 ET drag. Drag tires are measured across the tread. DOT tires (ET street etc) are measured across the sidewall.

I've done some measuring. 29" tall tires should fit with no problems. 30" is very close and with tire growth they may rub the front of the fenders (ground effects ect).

As for width, I ran 26x10.5 ET street's a couple of years ago and still had space between the fenders.

The best size is the tallest tire that can fit in the fenders then calculate the gears required for those tires. Then figure how wide they can go.

I think the easiest "largest" size would be 29x11 drag tires. The extra sidewall width on a drag tire would be getting close to the inner and outer fenders and if they start to rub it would only take a little bit of hammering to make them fit.



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87 IROC-Z Pro ET Bracket Race Car
383 stroker (carbed) with double hump cast iron heads and pump gas
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Best results before the 383 blew up
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Best MPH on a time slip: 117.87 altitude corrected to 126.10
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strokeronthesause

yes 28x12.5x15 will fit with 5 inch bs

askulte

Thanks for the help. I've got a 9" axle widened 1.25" per side (bought from a 4th gen friend), so the plan now is to get 15x10 Weld Draglites with a 6.5" backspacing, and some 28-11.5-15 ET Streets for the rear and 15x3.5 front wheels. Hopefully I can borrow a set of tires for SLP Day at Englishtown tomorrow. Let the racing begin!



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Andris Skulte
Skulte Performance Designs
Z28tt-89 IROC T56 DFI Twin Turbo
http://www.skulte.com