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fitting 40x13.5 17s

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black dawg

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I have been considering trying to do 40s on my 91 burb, basically for snow flotation. Already have a 60 and 14 bolt, and about 3 inches of lift over a stock 2500 burb. Trying to keep the lift amount to a minimum, and not opposed to cut out flares. How much lift do you guys think I will need? Do the cut out flares add much usable clearance?
 
Most guys on here hate body's lifts. But I can clear 39's on my truck with a 4 in lift kit and a 3 in body lift.
Never tried to run a 40 but I know that they would clear.
 
I get away with a 4 inch lift with no body lift on 40s. Just need to make sure your bumpstops are in the spot. Any fender cutting is almost always because of rubbing when the tires are turned or turned/compressed. Smaller lifts are going to require more fender cutting obviously because the tire is up in the wheel well more. Its not possible to run 40s and a 4 inch lift without trimming fenders....at least not if youre a pavement only guy, but even then you wouldnt get lock to lock steering without cutting a tire badly. Once you start flexing the trimming has to happen but low, big tire rigs are where its at.
 
Rim width and offset play huge part in getting away with minimal lift. If you run a narrow rim with stock offset you won't have to trim as much.
 
I think the tires call for a 8 or 9 inch wheel, and planned on very close to stock backspace.

Anybody use the cutout flares? I am not a fan of flares, but dont want the unfinished look of trimmed fenders on this burb.
 
They want you to run 9's. I run 8's because its easier to keep a bead when there deflated. I dont have any eperiance with the cutout flares but it looks like(google images) that they would work. You may have to trim the inner front portion of them. You should also have EZ inch blocks in the from moving your axle 1.5" forward. 40s wont fit without being moved up.

I have the ez inch blocks and a tired 4 inch lift so i think its right around 4-5 but just an fyi i lost the ability to have inner fenders because the tires are so big. I think that they would take so much work to get back in that i would just make some stainless ones instead. Also regardless of offset you will be hitting the front bottom of the fender, the front inner core support, and the bottom rear portion of the fender.
 
I dont know, maybe I am trying to do too much with this burb...it will see highway miles to get to where the big tires are needed, and is pretty clean so I hate to hack it up too much.

I had started building another burb (87), that is partly done, with plans of 42-47s, but was thinking maybe if I sized the tires down a little I could do it all with one burb, and not have to trailer anything. The 91 already has alot of cool stuff in it (injected 454, 4spd, tons with detroit, winch, air) But is only on 255 85 16s, which gets around fairly well, but bigger tires would make it easier and I dont think a burb is going to float the way I want it to without atleast 40s.
 
black dawg said:
I dont know, maybe I am trying to do too much with this burb...it will see highway miles to get to where the big tires are needed, and is pretty clean so I hate to hack it up too much.

I had started building another burb (87), that is partly done, with plans of 42-47s, but was thinking maybe if I sized the tires down a little I could do it all with one burb, and not have to trailer anything. The 91 already has alot of cool stuff in it (injected 454, 4spd, tons with detroit, winch, air) But is only on 255 85 16s, which gets around fairly well, but bigger tires would make it easier and I dont think a burb is going to float the way I want it to without atleast 40s.
Click to expand...

I feel ya. Thats why mine goes on a trailer now. 37s are a great tires size to think about. There great for offroad and the trimming is pretty minimal...
 
At 40 inches tall, regardless of offset of the wheel, and a roughly 5in lift, there will be some quite significant cutting. Or very very limited up travel due to bumps.
 
The H2 wheels would work for those tires.

I would go with a 1" body lift.

Martin
 
I run 39.5x15 TSL's on my K5 with a 4" lift and axles in the stock location. It took a significant amount of fender trimming on the front fenders to make them reasonably fit for off-road use. The rear of the front fender opening is cut back to probably 2" of the door opening along the bottom edge along with the inner fender being cut out in front of the firewall, and modifications to the firewall itself. The front "fangs" on the fenders need pretty good trimming for turning. I had previously run 13/38-16 TSL's, which are closer to 37" tall and pretty skinny, on the same 4" lift with slightly trimmed fenders and couldn't even get it turned out of the garage prior to trimming.

The cut-out style Bushwackers do provide more tire clearance but I really don't think they will provide enough for 40's with 3" of lift.

Regarding body lifts if they are a quality item and installed properly they seem to hold up fine, especially if you stay with the shorter 1-2" versions. These are very common in the Jeep world and I have never seen any failure on the trail associated with them. A friend of mine uses a body lift on his '78 F-250 trail truck (42" TSL's, 1-tons w/ lockers and chromos, built big-block, close to stock height suspension) that gets beat on regularly and has never had an issue. It is just a standard off-the-shelf 3" kit but he did cut down the lift pucks to 2".
 
The cut-out flares have you cut 1" of fender at front and back, which adds more like 1.5-2" on the back of the opening, since the rolled lip is removed with it.


Bushwacker.png


You can't go much further than this anyway, without removing or modifying the inner fender. You can cut away more in the front, though, so moving the front axle forward helps in fitting big tires. I have these flares, with close to 5" of lift and the front axle moved forward 1". It clears 38x12.5 , but I have cut additional material on in the front inside opening. I can't see 40's working with less lift, especially because they will be like 15" + wide. Some have tried to cut more than the directions indicate and pull the flares out further to fit, but they really don't conform like that.

The coolest thing is the reworked fender with stock-type rolled edges, but it's tons of work. The easiest thing is just cutting sheet metal and learning to like that "spartan" look. You do have to do something to seal up the bare steel, though.
 
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Blue85 is right, if you cut more than an inch or so not only will you have to modify the inner liner but the lip is exposed too. I cut about 2" across the top and 3"-4" from the each end off of mine.



 
So do you guys think I could get away with 6 inch springs and the cutouts? I am fine with moving the front end forward if I have to. That would only make it about 7 inches taller overall.

And I am fine with the cut fender look, just not on this suburban (yet). I wish I was talented enough to just rework the factory opening bigger.
 
For reference, my pics are 8" lift with 43's. The front axle is 2" forward and the rear is 3" back.
 
Ned Kelly said:
6.2Blazer,
Any pics of your low rider with those 39.5's?
Click to expand...
4" Tuff Country HD, 39.5x15 TSL on 15x8 2.75"BS wheels. I did say the bottom edge of the fender was about 2" away from the door opening...it's not in this picture but the rockers and bottom of the fender is cut out about 6" higher than stock, so prior to that it was about 2".

full
 
Here are some pics of my K30 with 39.5 TSL. The front springs are nearly flat, so 3" lift or so I figure.
You can see where the corners have had minor trimming.
I still have the sway bar connected, so that limits firewall tire rub to nearly zero.
Don't mind the rust. I've had the truck 25yrs now.

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