My 76' Gmc Sierra

I am wanting to buy a set of bigger tires for my 76 gmc sierra i have a 6" suspension lift on it and also have got a 3" body lift sittin in the shop for it if needed but i dont know if the tires i want will fit i got 36.5 ground hogs on a 16"x8" wheel on it atm and am wanting to buy 38.5" tsl sx tires and am putting them on 15"x10" wheel so i was wondering do any of yall think that they will fit without the body lift and no fender trimming.. and i am keeping it on the road no off roading...i have been rock crawling with it and been through twisted trails and my 36.5s didnt rub at all but i was j/w what yall thought..  

38.5 should work with little to no rubbing unless you off road then they will surly rub  

and i habe 4:10 gear ratio that should handle those tires fine,  

Cole673:
and i habe 4:10 gear ratio that should handle those tires fine,

You are kidding right??? Why do so many think that there is something magic about a 4.10? (like it is the holy grail of gears or something) The "magic" is when axle ratio is matched to tire size. 38's are in the 5.13 arena unless you want a slug that is hard on drive shafts, trannies and Tcases. A 4.10 with 38's is kinda like 3.07 gears with stock tires. Both are bad marriages.  

I think alot of the "magical 4.10 gears" is because most people don't know how to install new gears and the "4.10" is a really easy ratio to find in the junk yards so they buy the axles front and rear, and get home and install them in their trucks and the sad thing is, they had 3.73s wich only moved them one step lower. But atleast its lower. But now they want to put bigger tires on and don't realize they should be in the 4.56 or lower range already and they throw some big heavy 38s at it and now wonder it lugs around. Oh but you have that fancy high output motor! Sorry, I forgot there is those guys that think HP will cure it all. So, for those that are wondering.....
To solve most problems in the offroad world when you install big lifts and tires the Secret ratio for any wheeling is 4.10s. It might take you a minute to get to 65 but when you're there, you've used 10 gallons of gas and only running at 1500 rpms, but thats ok bake that tranny. And you can fit 38s on your truck with a 4" lift with no fender trimming. You may not be able to turn your tires but they fit. All in fun guys  

Well said!  

what is the good marriage of tire size for the 4.10 ratio then? like 33 or 35?