Can I fit 40" tires on my truck????

[80blackgmc]

Hey guys. I have an '80 GMC with 4" suspention and 3" body lift, with bushwaker fender flares. The truck came with worn 38.5" superswampers, and they fit fine. Right now it has 35" procomps on it, that look a little small for the truck.

I'd like to upgrade my wheel/tire combo to the maximum size I can run on this truck. I like the idea of a 40" goodyear MTR on 17" wheels, but will that fit my truck?

Any other tiresize/wheel size combos that would work. Remember, I want it to be the tallest possible and still keep a "street" tire. I don't do a lot off offroad, but I do some. Mostly the truck is for towing.

If I can't fit the 40s on there, what would i have to change on the truck to make it work?

 

[mikey_d05]

Short answer: possibly

Long answer: if you're pulling with a K5, I really don't think you want to be running 40" tires unless you have 5.13's in there or one hell of a stout engine. And I'm not sure the tire/wheel combo would fit. I hacked my fenders and relocated my front axle to make 39.5" boggers fit on a 6" lift. Somebody around here has probably done it, just give it time.

 

[4trolls]

I have 39.5s with 2" add aleafs and a 3" body lift , it all depends on if your willing to cut.

 

[highrider_44s]

just till they fit

 

[az-k5]

I am shoving 40" MTR's under my fenders with only 4" of lift. I won't even have to trim. I do need to move the axle foward an inch though to clear the floorboard/firewall.

 

[80blackgmc]

It has 4.56 gears and is getting a decent 454 (almost done).

Like I said, it already has big fender flares (with obviously cut fenders), so I don't see the need to cut. I could be wrong. 38s would "do", but I want that look.

Anyone with 38" or 40" tires and some pics??? Thanks.

 

[blazinzuk]

One thing to remember the narrower tires (MTRs) will fit better than boggers, I trimmed one of my old blazers to fit 36s and I am convinced you could run 38x12.5s on a stock rim with no lift WITHOUT moving the axle forward but the cutting involved would be quite complex.

 

[big_truxx]

My 75 came w/ 6" lift and 38.5" swampers. unfortunately I had to put a set of 35" radials on it for the 1500 mile trip home. When I get another pair of 38.5's I will try to get a pick for you if you still need it. I am looking at getting a pair of boggers for the rear and use two sx swampers in front as 2 are balder than heck atm. But they fit in there fine. I am sure 40's will fit in yours well also. You have 1" more lift than I and most likely more cutout on your wheel wells. Hope this helps somewhat

 

[80blackgmc]

Thanks. There is nothing like a test fit.....

 

[cegusman]

Here are some pics of my old k5 with 5" lift and 39.5 boggers.
Specs:
4" Front springs, 1" ORD zero-rate axle moved 1.5" forward
Stock rear springs echobit shackle flip with a 1" homemade zerorate
Lots of trimming