When we brought you the No-Lift TJ (Mar. '05, Apr. '05), 35-inch tires were the tire that we saw off-road the most. Now, with an increasing number of larger-than-35-inch road-worthy tires becoming available, and people building Jeeps with less lift for stability, we are seeing a lot of 40-inch tires on Jeeps with 4 inches of lift and some fender trimming.
We decided we'd raise the bar by putting 40-inch tires on a Wrangler with no lift for the ultimate in stability and ground clearance.So we ordered up a set of 40x13.50R17 Goodyear MT/Rs, mounted them on the new HD17 TrailReady bead locks, and quickly found out just how much sheetmetal really needed to go away to make this work.
A few of the goals we had going in were that we didn't want to "comp cut" the Jeep and we wanted to keep our gas tank under the Jeep where it belonged so our bulldog could ride in the back seat. Other than that, it was game on with the reciprocating saw and angle grinder.
The idea was to move the inner fenderwell up about 4 inches to the edge of the tub, and cut the tub until the tires had plenty of clearance. This Jeep is a jack of all trades, and in addition to rock crawling, we want it to be able to go down fire roads at speed and bomb through mud pits with aplomb, so we needed more than an inch of uptravel.
This fender moving is something that Trasborg has been looking to do for years, but when we got wind of Gen-Right Off Road putting together a high-clearance kit that included replacement inner fenderwells, corners that you could cut the wheel openings out of yourself, and larger tube fender flares to cover the bigger openings, we decided that now was the time.
This '94 Wrangler already had a 1-inch Daystar body lift on it, and a set of Mountain Off-Road Enterprises shackles, which together should have given about 1 1/2 inches of lift, but the sagging stock leaf springs meant we didn't get anywhere near that. We had 31 5/8 inches from axle centerline to the edge of the tub when completely empty. A bone-stock hardtop YJ has 30 1/4 inches from axle centerline to the edge of the body. Once we get everything back in the Jeep, we'll be lucky to see 1/2 inch over stock. We figure that's close enough to say we fit 40s on a stock Wrangler. Check out the clearance between the top of the tire and the wheel opening. A 1/2 inch isn't going to matter there.
After drilling out a bunch of holes to plug-weld the new fender in with, we cut out both the inner fender and the tub support, leaving behind flanges to weld to. | 
We welded a plug every 4 inches or so until the fender got too hot to comfortably touch, then stopped and let it cool. | 
We cut the leading corner off the old fender with the intention of using it on the new one. We could see the point where the three planes met on the new inner fender causing some damage. It turns out Gen-Right offers a piece of sheetmetal already cut and brake-formed if you want to chamfer the corner. |
Most of the modifications to the kit were needed because we put a CJ tailgate on the YJ. The Gen-Right Corner Guards for the YJ include the YJ tailgate hinge cutout. Since we didn't need it, we welded it up and ground it flush. | 
By taking the 40-inch tire, jacking it up, and tracing it onto the Jeep with a Sharpie marker, we were able to see how much to cut. This was our first mark, and we ended up cutting almost an inch higher than this in the end. | 
The 40 fits, but even with our re-drilled spring perches that moved the axle back 11/2 inches, the tire still needed to go back in the wheel opening. We used a Wagoneer main leaf, and some of the YJ leaves to make a bastard pack that moved the axle back an additional 2 inches for a 31/2-inch stretch in the rear. |
After welding, we used 3M Fast 'n Firm seam sealer inside and out to keep water out of our new, bare metal, welded seams. | 
With the stock Wrangler tailgate, you only need to prep, weld, and seal the latch on the driver side. On a CJ tailgate, there is one latch on each side of the opening, so we got to weld, grind, and seal twice. | 
It is important to protect the bare metal from rusting, so after the seam sealer set (about 45 minutes) we painted all the bare metal surfaces with a self-etching primer. Regular primer might work, but the self-etching stuff adheres to bare metal much better. It can be found at your local automotive paint store. |
This pinch seam protrudes into the new hole, so we pounded it up and welded it. We aren't concerned about anything beyond where we welded because the tire doesn't sit that deep into the wheelwell. | 
If it weren't for the fact that we already had the Gen-Right EXT gas tank in this Jeep, there was no way we'd be able to move the axle back as far as we needed to get the tires centered in the wheelwells. The stock gas tank couldn't take the Ford 9-inch in the stock location, much less 31/2 inches back. | 
We ended up having to cut about 11/2 inches out of our rocker protection where it intruded into the new wheelwell opening. |
Up Top, we had to cut 33/4 inches out of our stock cage's rear down bars to get it to bolt back in. We chopped them with a reciprocating saw, plug-welded in some sleeves, and then welded on the remainder of the feet to keep the rear seatbelt mounts. | 
We needed the back seat for the bulldog, but went with a Tuffy full-length underseat drawer to get the seat back in the stock position in relation to the inner fenders. The brackets included with the kit moved the seat forward, so we chopped them and moved the seat back almost 2 inches. | 
The obvious plus to using the Tuffy drawer is that we can lock our stuff up. The downside is that, once again, the CJ tailgate got in the way. We ordered a "scratch and dent" drawer to save some cash, and the mounting feet were what came dented. Not a big deal: We bent them out a little bit and the drawer cleared the tailgate just fine. |