I have an 8in lift in my truck that can allow for 38X14-15.50in tires. I have 35's up there right now and I can roast them on the road if wanted to. I want to go to a larger tire but want to still be able to "roast" em when i want to now. I have 4.10 gears In her right now w/ Detroit locker. I want same torque but want to step up the tire size to like a 37 or 38. I just don't know the right gear ratio to accomplish this burnout I want to do.

 

4.10 divided by 35 is = new gear ratio divided by 37
cross multiply

4.10x37=35x?
151.7=35x?
151.7 divided by 35=?
?=4.33

4.33 would be your new ratio with 37 inch tires

4.45 would be the new ratio for 38 inch tires.