If a tire had a section width of 10.2 on a 7 inch wheel would the section width increase or decrease on an 8 inch wheel?

The tire I'm looking at is a 255/60-R15

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1970 'Velle Project/Daily Driver
355 Vortec/ Comp XE262 w/1.6 roller rockers
Jet 200-4R Powertrax 10 bolt w/3.08
I'll have some track times SOON!

actualy it will stay the same but you'll get rid of the "bubble" effect of the 7" rim, i'd definately use the 8" rim. i do even with 235/60's on the front of my car.

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1970 SS396 AKA 454/4spd
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(OO=ss=OO)

Sounds good to me. Seems weird that BFG would advertise their section width based upon a certain rim size when different sizes would be the same. Thanks Chev-hell. By the way that thing you've got in your sig (OO=ss=OO)... that's just awesome.
----Ryan

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1970 'Velle Project/Daily Driver
355 Vortec/ Comp XE262 w/1.6 roller rockers
Jet 200-4R Powertrax 10 bolt w/3.08
I'll have some track times SOON!

I don't think the section width changes with wheel width. With a wider wheel the sidewall is straighter and the tire will flex less. The more buldge from the bead to the section width the more flex in the sidewall and maybe more rubbing when cornering...

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...Dennis
The '69 (http://chevelles.com/showroom/ww.jpg) & the '96 (http://www.camaroslimited.com/graphics/memcars/96ss.jpg)
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19Chevelle70, I'd get a few more facts before you decide.

On BFG's website and others they'll tell you that a tire section width will increase 0.2" for each 0.5" above the design rim width listed. So to answer your question, 0.4" is what you should expect.

I've found this to be a good relationship for 60 series tires. With 45 and 50 series the increase can even more, with 70 series and above a little less increase.

In case there still our doubts, get your hands on a tire at a shop that isn't on a rim. Grab the rim bead and move it wider, you'll see the section width growth clearly.

jlaf

Good to know jlaf. That little bit can definitely be the difference between rubbing and not rubbing.

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1970 'Velle Project/Daily Driver
355 Vortec/ Comp XE262 w/1.6 roller rockers
Jet 200-4R Powertrax 10 bolt w/3.08
I'll have some track times SOON!

<BLOCKQUOTE>quote:</font><HR>Originally posted by jlaf:
19Chevelle70, I'd get a few more facts before you decide.

On BFG's website and others they'll tell you that a tire section width will increase 0.2" for each 0.5" above the design rim width listed. So to answer your question, 0.4" is what you should expect.

I've found this to be a good relationship for 60 series tires. With 45 and 50 series the increase can even more, with 70 series and above a little less increase.

In case there still our doubts, get your hands on a tire at a shop that isn't on a rim. Grab the rim bead and move it wider, you'll see the section width growth clearly.

jlaf<HR></BLOCKQUOTE>

I'm sure I missed it but I spent a half hr on the BFG site and couldn't find anything on section width. http://www.bfgoodrichtires.com/ Any chance you can link to what you read?

On www.tirerack.com (http://www.tirerack.com) they list a size and the dimensions, height, tread width, section width for a the size based on a selected wheel width within a range of wheel widths. They don't mention it changing or not with respect to wheel width.

It leaves me wondering!! The test you suggest will give the results you suggest but is that what will happen when the tire is mounted and up to pressure? The footprint and the shoulder are much more rigid than the sidewall (just thinking out loud here... sorta!!) and sets the section width fairly well. With low profile speed rated tires the section width is designed to be almost the same as the wheel width and with most '60 series the tire sidewall seems to flex less with a wider wheel. The visual is less bulge...

Back to the question asked in the first post. Tirerack info says a BFG Radial TA 255/60/15 can be mounted on a wheel size of 6.5" - 10"'s. They put it on a 7.5" wheel and got a 10.2" section width. Of the 8 tires they sell that size 6 of them match that. One has a 10.5 section width and the other a 10.1 all on 7.5" wheels.

Quote:
Any chance you can link to what you read?
End Quote

The comment about the section width varying with wheel width is in the fine print at the bottom of the .pdf file listing the tire specs.

I can't link to it because the URL just stays at http://www.bfgoodrichtires.com/
while Adobe Acrobat launches..

Wes

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Thanks Wes,

I must have been tired not to see the .pdf link... I don't think they could have used a smaller font!!

Heres the .pdf for TA's and it says .2 for every .5 in the fine print!!
www.bfgoodrichtires.com/2001_PDF_files/Radial.pdf (http://www.bfgoodrichtires.com/2001_PDF_files/Radial.pdf)

Sorry I wasn't around for the follow-ups, but Wes did a good job with the BFG link version of this "section width rule".

Is anybody still unclear on this? For tight fits, this is a very important factor.

And I can't emphasize enough that when you finally decide to change to modern design tires (and most people someday will), with potentially lower profiles, it gets even trickier and the 0.2 per 0.5 isn't always accurate enough. The good news is you can loose the buldge and pick up tread width.

Consider a BFG Radial T/A 255/60/15 with its hard rubber 8.2" of tread width with a 10.4" section width (10.2 + 0.2 for change from 7.5" to 8" rim) on an 8" rim. Now consider 255/50/16 with varying rubber compounds. Guess what? Section widths can remain at 10.4"(depending on brand) and can be had with 9.5"+ of useable tread.

Now if burnouts are your thing, I understand. If hooking up is important (or handling), there are better streetable solutions to consider.

Recent articles in both Chevy High Performance and Super Chevy confirm my believe that 16" can be the sweet spot (read: best compromise!) for these cars. Cost of 16s (and even 17s) has greatly decreased in recent years as the big dollars push towards 18s and above

jlaf

These tires I'm mounting are going to be some D.O.T. slicks. They're for driving to the track and racing at the track only. The wheels I have on my car now are already 16 inch for daily driving.

In the Tire Rack site, if you look up a tire and get a listing of sizes there's a link marked "Tire Specs Key". It has tons of details and covers the .2" section width to .5" rim width variations.

[This message has been edited by Glenn1018 (edited 07-05-2002).]