FlamedROC

I'm sorry if this question is asked alot but I did a search and couldnt find an answer to what I was looking for!

I have a chance to get some Drag radials and was wondering if the tire size of these tires would fit in a stock 86 IROC (Clearing fenders well etc.) Will they fit right in or do I have to modify the chasis to make these fit?? Should I get them or not

The Tire size is 11.5/28.5-15 firestone Drag Radials w/ a # that reads PT-80 on the edge near the bead (what does PT-80 mean?)

AlkyIROC

"drag radials" are a DOT tire and will have a typical passenger car tire size on them 235/60R15 etc.

A drag slick will be sized like 11.5 x 28.5 x 15.

A DOT tire size is metric. 235 is the section width (width across the sidewalls). 60 is the aspect ratio (height of the sidewall). To get a better understanding on the actual tires size;

235 = 9.25" wide (not the tread but the entire width of the tire)
The aspect ratio doesn't mean much except a shorter sidewall is better for road course handling since there's little to no tire roll. A drag tire does better with a tall sidewall.
To figure out the total tire height, 235 x 60 / 2540 x 2 + 15 = 26.1" tall

A drag tire uses different measurments. 11.5 x 28.5 x 15. 11.5 is the width of the tread. The section width will be more and you need to look at the manufacturers spec sheet to get the full width. 28.5 is the tire height but again a spec sheet must be read for the true height. It can be about an inch different from the size on the tire.

Both examples were using a 15" rim.

Back to the "drag radials". Firestone doesn't produce drag radials. Firestone hasn't produced a drag slick in years. The new brand is Phoenix. If they are "Firestone" tires then don't waste your money on old dried out tires. Buy some new slicks.

As for what size tire fits depends a lot on the car setup and the rim choice. I run a 29 x 9 x 15 Hoosier on my car with a 15 x 10 rim and 5.5" backspacing. I had to trim a bit of my fender because my rear axle is set back about an inch. Standard tire height for a stock third gen tire is 26". A 28" tire can be squeezed in but may need some fender massaging.

FlamedROC

Thanks for the info man that helped alot!!!! ok Yea the tires are slips my bad. The firestones are really old I think from the late 80's but they were goin to be free so I didnt want to pass the offer up. so would you recommend putting a 26x10-15 on or what would you recommend for my car... I dont want to cut or modify the car at all but want to fit some slicks back there!!

AlkyIROC

A 26 x 10.5 x 15 MT ET Street will fit with no problems. I'm not sure about a 26 x 10 x 15 ET Drag.

FlamedROC

isnt a 10.5 bigger than a 10 though

AlkyIROC

Drag tires and DOT tires are measured differently. The 10.5" is a DOT tire. The 10" is a drag tire. The measurments are not taken from the same place.

26 x 10.5 x 15 ET Street;
Sidewall width = 10.5"
Tread width = 8.3"
Overall diameter = 26.1"

26 x 10 x 15 ET Drag;
Sidewall width = 11.6"
Tread width = 9.6"
Overall diameter = 26.0"

Since most people use Mickey Thompson tires you can check out the tire dimensions at http://www.mickeythompsontires.com

Goodyear and Hoosier also have tire specifications online for their drag tires.

FlamedROC

ok I got ya thanks for the site that helped out a lot. sweet.. yea my goal is to get some slicks back there to hook up and get a real good ET. I have no clue on what I would run with a stock TPI 305 w/ auto on slicks but it should be semi quick. low 15s maybe high 14's???