Any guesses on this wheel width and backspace?

[clint w]

I like the look of the wheel and tire. The owner of the car said it's a 275/60/15. Any guesses on wheel width and backspace? Maybe someone here has a similar setup. I've never seen a deep dish wheel like that on a first gen that wasn't sticking out further. Maybe the rear end has been modified? 

[Scott S.]

My guess would be an 8"-8 1/2" wheel on a 3" backspace...... Narrowed or another type of Chev differential. 

Does look cool, though.

[MCfan]

Clint, assuming a stock rear axle, my first guess is that is possibly a 275/50-R15 (25.8" tire) on a 9" rim with 5.0" backspace (0 offset) which would give a 5" deep "dish" but only 1/4" clearance with the lip of an untrimmed wheel well opening.  When I compare your photo with a similar photo (attached) of my 275/60-R15 on an 8" rim with 5.0" backspace (+12 mm offset), yours looks shorter (which also makes the tire look fatter).

If it is a 275/60-R15 (28") tire, it could still be on a 9" rim with 5.0" backspace (0 offset), a 5" deep "dish" and 1/4" outside clearance.  A 28" tall tire (vs 25.8" for the 50 series) with the same tread width would not look quite as fat.

If it is a 275/60-R15 tire on an 8"rim with a 4.5" backspace (0 offset), it would only have a 4.5" deep dish with 1/4" outside clearance. 

NOTE: I would not personally use ANY rim width/backspace combo that leaves only 1/4" of clearance with an untrimmed wheel well opening because of body shift during cornering or hard acceleration.

The photo below show my 275/60-R15 mounted on an 8" rim with 5.0" of backspace (+12 mm offset) which give right at .75" of outside clearance with the untrimmed wheel well opening.  Of course,  going with 5.0" backspace on an 8" rim reduces the depth of the dish to 4.0" but our Montes have more room inboard for fatter tires than they have outboard so an offset of +12 mm is recommended for any width of rim.

Now, if that car has a trimmed wheel well opening (1" is about maximum) he could be running a 9" or 9.5" rim with a small amount of negative offset (i.e. -6 mm or -12 mm offset) to achieve the deeper "dish" look.  A narrower, non-stock axle could increase the depth of the dish but it will still be the size of the wheel well opening and the position of the rim/tire combo that dictate operating clearances.

In the final analysis, it matters not how cool a wheel/tire combo looks if it won't work - you can't BS a tape measure! 😄