... by lower profile do you mean ... 70 instead of 75? I have been searching for tires and having a heck of a time finding reasonably priced tires in the the 225 range that are all terrain. that is another reason I have been looking at the 235s
235 is the section width in millimeters. 235/25.4 = 9.25 inches wide
70 (or 60 or 75) is the percentage of the section width between the wheel and the ground. It's called the profile 'cause it's what you see from the the side.
So, overall 235/70R16 tire diameter is: 2 x [(235/25.4) x 0.70] + 16.0 = 28.95 inches
Whereas 235/75R15 tire diameter is: 2 x [(235/25.4) x 0.75] + 15.0 = 28.88 inches
The difference is 0.070 inches -- just over 1/16th inch, and negligible IMHO.
Tire sizes are approximate, even in the best case.
BFG makes an AT (my tire, the T/A KO) tire in 235/70R16. It's widely regarded as a good all-'round tire, except not so great in the mud. But I live in/near the desert. Costco and America's Tire Co. have the some of the best prices on BFGs. I've bought from both, with Costco being slightly cheaper -- more so if you can wait for a sale. Costco stars a 3-week Michelin coupon sale on Jan 5, '09. BFG tires are often included as well. Sales typically happen a few times a year.
You may still need someone to verify the tire size with an unmodified Sidekick (Samurai here).