Hello. I have a 1989 IROC that was originally equipped with the very rare 15" IROC wheel. I am planning to convert the car to the 16" IROC wheel. The car also has aluminum drums. According to GM PDI, there are two different front control arms, one for the 15" wheel and the other for a 16" wheel. Has anyone out there ever gone from the 15" to the 16" rims and had to replace the front control arms to accomodate the 16" wheel? Were there any clearance issue with the front tires? 
JamesC
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Apr 15, 2026
Quote:
No clearance issues.Originally Posted by 89IROC5.0TT6s
Has anyone out there ever gone from the 15" to the 16" rims and had to replace the front control arms to accomodate the 16" wheel? Were there any clearance issue with the front tires? JamesC
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I wondered about that myself when I switched to the 16" wheels on my 89 RS years ago. Physically, there's zero difference in the actual control arms. The only thing GM did different on the cars equipped with 16" wheels from the factory was they put a longer spindle stop on the control arm to keep the wider wheel from rubbing when you turn the wheel all the way to one side. The steering stop is just a piece of metal that's riveted to the front lip of the control arm. Even with the shorter 15" stops, my wheels never rub when turning.
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Black Betty
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Dec 18, 2009
- Join DateFeb 2007
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- Car'86z28 blacked out/'87 iroc yellow
- Engine'86-305 4bbl, '87-305 tpi
- Transmission'86-tremec tko600, '87-700r
- Axle/Gears'86-3.23, 87-? stock gear
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My car came with 14s i had no clearance problems when i put on a set of 16s. Go for it
Thanks for the heads up. Guess I'll have to go that junk yard in Ogden and get a close up.
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Well Assuming how other manuafactures put different size rims on their car Im sure the difference between the 15 and 16 is compensated through the tire.
Because ifthey make a car with 3 different size wheels they are gonna run into calibration problems.
So if the car cam with 16s and 17s the 16s would be like a 255/50 tire and the 17 would come in a 275/45 so make up for the overall height of the tire. Unless you are worried about width. But im sure the difference isnt much.
Jay
Because ifthey make a car with 3 different size wheels they are gonna run into calibration problems.
So if the car cam with 16s and 17s the 16s would be like a 255/50 tire and the 17 would come in a 275/45 so make up for the overall height of the tire. Unless you are worried about width. But im sure the difference isnt much.
Jay