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Discussion Starter · #1 ·
If a tire is advertised as having a 10.8" section width, will it have the same section on both a 7" and 8" wheel?
 

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No.. only on the specified wheel width...
 

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and for your next question.

0.5" increase in wheel width causes a typical increase of 0.2" in tire section width.
 

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Discussion Starter · #4 ·
Thanks Steve. Here is my dilemma. I am looking at American Racer L-60-15 DOT tires. The brochure says 'rim widths' 7-8, 'section width' 10.8 and 'tread width' 9.5. It does not specify that the section width was taken while mounted on a 7" or 8" wheel. Since the tread width is 9.5 I probably should use the 8" rim so I have less than 1" on each side of the wheel. The 7" wheel would probably be too narrow for a 9.5 tread.

I am currently running 28x11.5x15 ET Streets on AR TTII wheels with 3.75 bs. I have a 1/4" spacer and the tire still rubs some on the frame. These tires have a section width of 11.1 and I cannot get them to hook (1.9-2.0 60') so I wanted to try the American Racer DOT. Someone at the track is using this tire and gets 1.6-1.7 60' on his 60s Nova with about the same mph that I run (92-93 in 1/8th). These tires are REAL soft.

OK, now you know the whole story. Comments?
 

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Have you ever tried a set of slicks?? If so was your et any better? From looking at your sig, 11.96 @ 117 it seems like you have some sort of issue with traction that might be more than just tire related. I have heard that the MT ET streets work very well so maybe you have suspension issues. Are you still running stock lower control arms? Do you have the front sway bar still on and what shocks are you running?

More info please,
 

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Another thing that might help rule out tires or not would be to meet this person at the track and each of you make a pass with the others tires and rims. If you both run the same as always then you can be sure that it is not tire related.

Just a thought, dunno
 

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Discussion Starter · #7 ·
I have Southside bars and right side air bag with 16# air. Front sway bar is still on. When I do a small burnout on the street, both black marks are the same density, width, and length. The suspension seems to be working OK if you can base that assumption on the tire marks.

I have also tried BFG 275-60-15 DRs and I still no luck with traction. I have not tried slicks because I don't wnat to haul them to the track. :(

I don't think the guy will want to change tires with me.
 

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Discussion Starter · #8 ·
Forgot about the shocks. I have KYBs at all four corners. Thanks for your help.

<small>[ March 30, 2003, 06:54 PM: Message edited by: GNCOL ]</small>
 

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wonder if the air bag pressure is causing the tires to unload? You might try dropping the air bag pressure to 8# and see what happens.
 

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Discussion Starter · #10 ·
I'll drop the air pressure to 8# next time at the track. Thanks Steve.
 

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Wider is not always better. My 9" Hoosier slicks hook much better then my 28x11.50x15 Hoosier quick time pro's. Once you hit the 11's you need slicks on the track. If I run a street tire class I have to give up 4-5 tenths due to tires. Also on the street nothing will really hook up. As Steve said drop the air in your air bag. Also try and remove the front sway bar or get a hollow F-body sway bar. If you don't spend too much time on the street you can try 90/10 shocks up front. What did you set your pinion angle at with the Southside bars?
 

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Discussion Starter · #12 ·
Ed,

I don't remember what the pinion angle was set at since it has been over ten years since I installed them. I only drive the car about 3,000 miles per year to cruises and the track for test and tune occasionally. I may try replacing the front bar with an F-body bar. Thanks for the help.
 

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There is a rule of thumb that says the wheel width should not be less than 70% of the tire width. That means for a lot of TRs, the 275 DRs should be on at least a 7.5" wheel wink

I agree with Ed about wider not being better. I went from a 275 Nitto to a 9" QTP and gained on the avearge .2 in the 60' with a lot less reliance on track prep. The next step will probably be a 9" slick but expecting an equal gain would probably be a little greedy :D
 
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