Tubbing Your Toyota Fenderwells
Http://www.4x4wire.com/toyota/tech/fender_tub Short Cuts
Author: Jay Kopycinski February 2001

One of the biggest issues with adding bigger tires to a second generation truck or first generation 4Runner is the interference between the tire and the rear edge of the front fenders. Common practice is to start by hammering down the seam where the tire hits the fenderwell. This is usually followed by taking a bigger hammer and pounding even harder to gain more clearance. Finally, many people move their front axle forward an inch or so to gain even a bit more clearance.  

However, if you run 35 inch tires or larger, small lift, and/or have lots of useful upward travel, this still may not be enough. This article discusses how to enlarge or "tub" your front fenderwells.  

Special thanks goes to Brian Ellinger who originally gave me many of the ideas you see here.  


The first step is to decide how much you want to enlarge your fenderwells. After looking at the body and fender panels and the location of the closest body mount, I determined I could cut the lower edge back about 3 inches without having to relocate the body mount. I did, however, have to cut into and reinforce the mount.  

Outer fender removed to start the project

To make cutting and working on the fenderwell easier, I removed the outer fender sheetmetal as shown in the picture here. To remove the fender, remove the four bolts along the hood line, two or three bolts up near the turn signal, bolts at the rear lower edge of the fender, and the one bolt inside the door jam near the windshield.  

Before you start cutting be sure to check for wires and other items behind your fenderwells. Pull back the carpet and floor padding in the area you're working on, and check from time to time while you're cutting or welding to make sure nothing catches on fire in the truck interior.  

Cutting & Welding

I can't really describe how to make the cuts you need in your fenderwells. When I did the first side I cut a reasonable, but smaller than I anticipated, hole in the metal. I then kept progressively enlarging the hole until I got it to the point I wanted it. On the second side, the job was quicker. I simply marked my area and started cutting out the whole piece the first time.  

Patch panels welded into place

Once the final hole was cut in the fenderwell, I took some 16 gauge steel sheet and hand formed it as needed to mate to the area. On the driver side I was able to patch the area using a single piece with a simple curve in the sheet. However, on the passenger side (shown in picture here) I had to add a second small piece at a right angle to the large piece in order to close the area.  

The sheet was welded to the remaining original body metal using a wire feed welder. Small stitch welds were placed periodically along the seams. In some cases it was useful to weld a portion of the panel and then lightly hammer form it and tack as I proceeded. Again, check from time to time to make sure nothing catches on fire in the truck interior.  

Finishing the Interior

panels.jpg inside.jpg
Driver side uncut and passenger cut panel Cut panel reinstalled in the interior

Once the panels were welded in place, I used 3M Automotive Joint & Seam Sealer to completely seal the seams. I purchased a tube of this material at my local body and paint supply store. With the inside sealed, I trimmed and reinstalled the carpet and padding. It was also necessary to trim the plastic kick panels to match the contour of the new footwell areas.  

Finishing materials for the fenderwell

With the outside seams sealed, I simply shot the underside of the fender areas with Duplicolor Professional Undercoat spray.  

Lower Fender Mount and Fender Trimming

I knew that once I trimmed the outer fender sheetmetal I would lose the lower fender mount holes. To provide a new mount I used a trick Brian showed me. I welded a short tube to the side of the body metal. On the end of the tube I welded a 5/16" hex nut. This "post" will now serve as the lower fender mount.  

mount.jpg fender1.jpg fender2.jpg
Mount used to secure lower portion of fender View of the mount and screw securing fender Fender after final trimming complete

I replaced the outer fender sheetmetal and marked and drilled a hole as need for the lower mount. I secured the lower fender using a 5/16" stainless button head bolt. I then used masking tape and a pen to mark out my new fender opening and trimmed as needed using a sabre saw and die grinder. The inner plastic fender liners were discarded.  

In my case I also chose to trim some inches off the trailing edge of my front bumper and the front edge of my nerf bars.  

Viola......Tubbed fenderwells and wider fender openings ready for bigger tires......Without more lift.  

Thanks for reading! 


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