Biggest slicks
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Junior Member
Joined: Jun 2001
Posts: 86
Likes: 0
From: Stow, OH USA
Car: 1986 IROC-Z
Engine: 383
Transmission: th350
Biggest slicks
What is the biggest slick you can fit on a stock rearend IROC.
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Britt Vanmeter
'86 IROC-Z with a 383 and NOS
http://orangeroc383.fbody.com
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Britt Vanmeter
'86 IROC-Z with a 383 and NOS
http://orangeroc383.fbody.com
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Joined: Jul 1999
Posts: 17,274
Likes: 171
From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
I have 15x10 rims with 5.5 backspace and use 28x9 slicks with lots of room.
The height of the tire will depend on your gear ratio and shift points. You won't want 28" or taller tires with anything less than 3.73 gears and even that might be pushing it.
Since the lowest gear ratios available for the 10 bolt are 3.73, 4.10 and 4.56, you need to determine what tire size works best.
When I was running a 3.27 geared 9 bolt and 26" tall tires I needed close to 3.90 gears with those tires. When I switched to a 10 bolt with 4.10 gears I went to 28" tall tires and I my shift light comes on just as I cross the 1/4 mile shifting at 6400 rpm. I want to go taller. When I eventually put in a 9" with 4.56 gears I can go to 29 or 29.5" tall tires and have the same results.
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Follow my racing progress on Stephen's racing page
and check out the race car
87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block
Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546
Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association
87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley
The height of the tire will depend on your gear ratio and shift points. You won't want 28" or taller tires with anything less than 3.73 gears and even that might be pushing it.
Since the lowest gear ratios available for the 10 bolt are 3.73, 4.10 and 4.56, you need to determine what tire size works best.
When I was running a 3.27 geared 9 bolt and 26" tall tires I needed close to 3.90 gears with those tires. When I switched to a 10 bolt with 4.10 gears I went to 28" tall tires and I my shift light comes on just as I cross the 1/4 mile shifting at 6400 rpm. I want to go taller. When I eventually put in a 9" with 4.56 gears I can go to 29 or 29.5" tall tires and have the same results.
------------------
Follow my racing progress on Stephen's racing page
and check out the race car
87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block
Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546
Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association
87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley
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