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 Post Posted: Mon Feb 09, 2009 3:57 pm 
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Whats a safe tolerance of mis match, I've just seen some wheels advertised for sale with a 16in tyre on a 12in rim ?

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 Post Posted: Mon Feb 09, 2009 4:24 pm 
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Most of the tire company's will have a rim width listed....I have a 16x33 and Hoosier listed it to have a 15" wide rim   :-k

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 Post Posted: Mon Feb 09, 2009 5:35 pm 
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From what I was always taught, you always wanted to have a rim that was 1"-2" narrower then the tire width.  This allows you to maximize the use of the side wall for more traction.

Don

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 Post Posted: Tue Feb 10, 2009 4:37 am 
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going off of the Hoosier website, it looks like anything under 12in wide, 1in is roughly the variation. At the upper end they list a 17in wide tyre with a rim with of 15-16in

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 Post Posted: Tue Feb 10, 2009 8:28 am 
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The tires on my Camaro are 33x16x15 but the actual contact patch is 17 inches wide!  I got them mounted on 15x15 weld wheels but whether something else would work better or not I got no clue?  I have had 1.15 short times though.

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 Post Posted: Tue Feb 10, 2009 3:29 pm 
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I've had a 33-17-15 on a 14 inch wide rim.. only for a couple of runs tho didnt give me any problems, they had been run on those rims for a while before.

now got a 33.6-16-16 on 16 -16 rims.. seems fine as well ..

the circuit boys (sportsmen classes) used to run an 8 inch wide tire on a 10 wide rim as when its inflated you do not get any flex in the side walls so its not going to step out of line due to sudden side wall movement. as we dont do corners I'd go a couple of inches wider on the tire without any worries, that would give a good footprint at launch and also give you decent growth for the top end.

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 Post Posted: Wed Feb 11, 2009 3:13 am 
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The wider the rim, the stiffer the sidewall seems. This is why big power cars with tire restrictions run them. There is a difference in tire pressure to get the best foot print with different size rims. It also changes your diameter, the wider the rim the shorter the roll out.

It's a tool used on circle track cars to change stagger and they get a kind of tire shake on the right rear, a wider rim sometimes cures this with out adding tire pressure or stepping up wheel speed.

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 Post Posted: Wed Feb 11, 2009 7:10 pm 
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What I am starting to notice is with my heavy car with a 16.5 tire on a 14 in. rim the sidewall is absorbing the "hit" before the shock is and causes the tire to unload a little thus the tire spins somewhat after the "hit".   Probably going to a double adjustable shock or more narrow tire would help I hope.  I need tires now so that may be the route I take first.  So my answer is, with a heavy car with a wide section width tire and a narrow rim seems not to be the best choice.


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 Post Posted: Fri Feb 13, 2009 6:42 am 
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82Blackbird wrote:
What I am starting to notice is with my heavy car with a 16.5 tire on a 14 in. rim the sidewall is absorbing the "hit" before the shock is and causes the tire to unload a little thus the tire spins somewhat after the "hit".   Probably going to a double adjustable shock or more narrow tire would help I hope.  I need tires now so that may be the route I take first.  So my answer is, with a heavy car with a wide section width tire and a narrow rim seems not to be the best choice.


This could be as simple as an air pressure thing. Most times the side wall distorts, it's hooking too good. Tire contact patch bites and sidewall distorts, then distorting contact patch. It all starts because your wheel speed falls below optimum tire slip angle. (dead hook)  There is the possibility that your instant center is too high and that would show as rebound in the rear of the car, Either way, adjustable shocks for this is like taking abtibiotics instead of boiling drinking water when you get Cholera.

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 Post Posted: Sat Feb 14, 2009 1:01 am 
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Yea,.. you need to be up on the tires while leaving the line.  A dead hook when leaving the line might sound good but doesn't result in better ETs.  It just boggs the engine.  You can tune this with tire pressure like has already been said.

Don

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