So I read the tire forum, and my answer was left a mystery. In the forum, it did not say if my 87 S-10 Tahoe Blazer would need a lift kit for 31x10.5x15's. I've seen these trucks with this tire before, but I guess I never thought about the lift til I got the tires next to the truck, and also, the torsion bar crank, does that also apply to my year Blazer.... It did not say in that thread either. Thank You for your time. I got my 31" tires outside and I am getting them put on the stock aluminums on Wednesday. FYI there used tires, so I would say there probably about 30" Cause there is about 3/8" of tread left on them.

 

Regardless of year the largest tire to fit without modifications is a 30" tire.

To fit a 31" tire without rub you need a 2" lift, either a body lift or suspension lift. I do not recommend lifting by a torsion bar crank.

To fit a 32" you need 5" of lift.

To fit a 33" tire, 6" of lift and fender trimming.
I put on 33" with a 3" body lift and massive fender trimming, plus I beat the firewall back about 1".

That applies to every year S10-Blazer, both the old and new body styles.

ZR2 are different. They already have a 2" lift, and a wider frame.