Bigger Tires on 4Runner? (Cutting & Trimming)

 In 5th Gen Mods, Maintenance

Bigger Tires on 5th Gen 4Runner (Cutting & Trimming)

Fitting Bigger Tires on 5th Gen 4Runner

Exactly what to cut, chop and remove to fit bigger tires on your 5th Gen 4Runner (34″ Tires)

We are talking about: 

  • Trimming the 4Runner Body
  • Trimming Plastic Valance Caps (Rocker Panel End-Caps)
  • Body Mount Chop (BMC)
  • Remove Splash Guards (Rear Fender Trimming)
  • Push in Fender Liners
  • Trimming 4Runner Fender Liners

Recently, we wrote an overview for fitting bigger tires. In this post, we covered tire size, tire specs, wheel sizes and how they work with tire sizes, and much more. In that post, we really explained what the largest tire size was, that you can fit on a stock 4Runner. We also talked about going a step further with bigger tires and lift kits and leveling kits.

Bigger tires with a lift kit or leveling kit?

If you are looking to swap out your factory 31″ tires with 33″ or 34″ tires, this overview is for you. We have the 285/75R17’s (34’s) on our 2014 TEP and had lots trimming to prevent rubbing.

To run 34’s on your 4Runner, you need at least a 3″ suspension lift and even with that, you will need to do serious trimming to your 4Runner’s body, plastic valance caps, body mount and the splash guards.

We wouldn’t trust 2″ leveling kit or 2″ suspension kit with 34’s. They are pretty big. We have trimmed the 4Runner’s body, plastic valance caps, body mount chop, removed both splash guards (rear wheel well liners) and pushed up the front plastic portion of the wheel well liners. And, it was still rubbing. The main problem you are going to see is with the front fender liners, they need to be cut back quite a bit.

Every time we go out, we have done a little more trimming each time. It has gotten to the point that I am going to throw some strut shims up front .25″ stacked on both sides. And, then install a new 3″ overland spring in the read to replace our icon stage 2 suspension lift 2″ spring.

Trimming 4Runner Body

Body Mount Chop + Trimming 4Runner Body?

This is a pretty interesting mod. One of the first mods that had us rethinking this whole goal. We have to trim the actual 4Runner body. Anyway, we did it and it was not that big of a deal. Just get it over with. You will be much happier with 34″ tires than that missing piece of 4Runner.

Trimming the 4Runner body is important for a couple reasons. To start, if you do not trim your 4Runner’s body, you will have an unproportioned look on the wheel well. Also, not trimming your 4Runner’s body will eventually lead to slight rubbing when your wheels are at full flex and wheel lock (when your tires are fully turned, driver or passenger).

Trimming Plastic Valance Caps (Rocker Panel Caps)

Rocker Panel Caps After – And, they were still Rubbing at flex

4Runner Body Mount Chop - Valance Caps

You will need to trim your plastic valance caps. Some people call them Rocker Panel Caps, and some people call them valance caps. Either way, you will need to trim these pieces of plastic that interfere with your larger tires.

This took a few attempts to get right. We started small and then ended up cutting as much off as we could, without being able to notice the cuts from the outside.

Body Mount Chop (BMC)

Body Mount Chop - Driver

This one goes without saying. You will absolutely need to chop your body mounts. Toyota extends the housing around the body mounts into the wheel well quite a bit. Most of this housing is just wasted space. You can take quite a bit of this housing off and give yourself plenty of extra space in the wheel well.

Companies like Metal Tech 4×4 have body mount chop kits, but any reputable 4×4 shop should be able to cut them apart and then cap them. If you don’t know how to weld, then you should probably take this to a shop that can do it for you. The cost is pretty cheap ($100-$200), and any good shop should have a body mount chop done in a couple hours.

Remove Splash Guards (Rear Fender Trimming)

Yeah, it doesn’t look good, does it? So, this was my first lesson in letting someone else chop my body mounts. If you see the Sawzall marks just above the body mounts, that was a clumsy guy, who will never touch this 4Runner again. Not a very big deal, just pretty annoying. Everything else is about how it will look after some serious trimming.

The splash guards and rear fender liner are located in the rear housing of the 4Runner wheel well. These look like your front fender liners. Some 4Runner’s might have the actual mud splash guards. If you have these mud splash guards, you should just take these off.

The inner fender liners on the rear wheel well are thick plastic pieces of plastic that prevent mud, dirt, and grime from hitting your inner body. But, the inner body of the 4Runner is well-protected how it is. So, removing these plastic pieces is not that big of a deal.

Push in Fender Liners & Trim

Squadron-R Fog Light Install Step #10 - Remove Fender Liner

Fender Liner Step #1 – Pushing the Fender Liners Back

The front fender liners will take quite a bit of adjusting. To start, you need to locate the hole that your 10mm bolt is going through your body and up into the fender liner. You want to take loosen that 10mm bolt and push back your fender liner as much as possible. Literally, push the fender liner towards the front-end of your 4Runner. Once you are not able to push any further, mark the spot on your fender liner with a white sharpie (or something you can see on black), through the h0le in your 4Runner body (where the two met).

After you have marked your spot, let the fender liner out again. Using a plastic drill bit, drill a hole in your marked spot. Use a bit that is less than the width of your 10mm bolt for your bolt to feed through and catch on. After you have the hole punched, tighten everything up.

Note: There are two bolts that go through the body and into the fender liner, You may need to drill two holes for both bolts that secure the body to the fender liner.

Fender Liner Step #2 – Cutting unwanted section from front well Liner

Trimming Front Fender Liner 5th Gen 4Runner

After you have your new spots located, and mounted, you should start driving around and see if it is rubbing. After doing this, our 34″ tires were still rubbing.

Steps for trimming your fender liners:

  • Back out of your driveway and lock your wheels passenger or driver, you will start to hear rubbing.
  • If your driveway doesn’t work, drive around and find a spot where your tires start rubbing.
  • As soon as you start to hear your tires rubbing, stop.
  • Get out and mark the location on the fender liner.
  • Pull back into your garage and cut off 1″ or more of that section.
  • Repeat these steps until you don’t hear rubbing anymore.

We had to cut off a good six inches of fender liner before we stopped hearing our tires rub. After dealing with a couple months of our tires rubbing, we then moved to another inch our Icon Stage 2 Suspension Lift.

Pinch Welds on 5th Gen 4Runner (Hammer or Bends or Cut?)

Pinch Welds on 5th Gen 4Runner (Hammer or Bends or Cut?)

It really depends on how bad your tires rub with this area. We thought we solved all our rubbing problems, but then we added the wheel spacers. After the spacers, we started rubbing more on the fender liners and these pinch welds.

There is one area of the pinch weld that sticks out a little further than the rest of pinch-weld area (top image circled). In the top image, you can see the portion that I “bent”. I just grabbed two pairs of vice grips/ clamps and peeled it back. If I am still rubbing at flex, I will probably go back in and bend both sides all the way back in towards each other or outside of each depending on how the tire is rolling past it. I would not slam this with a hammer or cut it off until I have to.

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Showing 18 comments
  • William
    Reply

    On the side note, if you run 285/70/17, then you won’t have to worry about rubbing or body chop. Just run a 2 inch lift and it will be fine. Hope that helps decide when going for 285/70 or 285/75

    • Brenan - Trail4R
      Reply

      William,
      Yeah, even with the 285/70/17 tires, there are still a few guys out there that have rubbing on the front fender liner. It’s weird, some guys have issues with them and some don’t. It also depends on the tread pattern and exact tire size. Some 33″ tires are closer to 34″ tires. It really depends on the actual brand of tires and tread pattern at the 33″ sized tire. The 33″ tire size is a touchy subject, literally

      • Mtnmn
        Reply

        Very accurate! I just put a 3″ lift on my 2017 ORP and have rubbing issues on the passenger-side body mount and driver-side fender with 33″ Cooper Discoverer STT Pros. They’re measured @ 33.03″ on a 8.5″ wheel, but im using stock 7.5″ with 1.25″ spacers. My alignment put the driver-side @ 3 degrees caster and the passenger at 3.8. It could be the extra caster, but I’m working to trim and clear as needed.

  • Jay
    Reply

    I have BFG AT KO2s 285/70/17 on my 2012 4Runner trail with Icon stage 2 Suspension lift and it rubs. I trimmed away some access plastic in the front wheel wells but even so this weekend I got flexin and my front tire swallowed up my passenger side mud flap. Brrrrrraaaaappppp snap goes mudflap, lol. I did not see any rub marks on the frame however so I’m still hoping no body chop is needed.

  • Joe
    Reply

    I just put 285/75r17 on my 5th gen 4runner. 3” suspension lift and body mount chop. Going to mod the fender liner, but as you pointed out in the rocker panel cap photo, mine rubs past that and onto the exposed metal. Any thoughts on solving this? Cutting it down to as close to th bolt possible? Great write ups though. Thanks!

    • Brenan - Trail4R
      Reply

      Joe,
      I don’t have experience in cutting that piece of metal off yet. Let me take a look at that and get back you…

  • Paton
    Reply

    I just ordered the readylift sst 3″/2″ kit for my 2017 4runner offroad. What kind of modifications will I need to fit 285/70/17 BFG AT KO2s? Also, is there an optimal wheel width and offset to maximize tire size on 17″ wheels? Thanks!

    • Brenan - Trail4R
      Reply

      Not much trimming for that set-up. Fender liners will likely need to be slightly pushed forward, and possible BMC. Wheel width typically should not exceed 9″ for that tire size. I would go with a 7-8″ wheel width but 8.5″-9″ will work. Again, I wouldn’t push 9″. For offset, it really depends on what wheel you decide on and what that company offers for offset options. I would look for -4 to -12(ish) depending on the look you are going for (the more -offset the wheel has, the further the wheel will sit outside the wheel well). For backspace, I would keep it around 4 to 4.875″ (The smaller the backspace, the more the wheel will sit outside the wheel well).

  • Jorge
    Reply

    Hello, I just get all terrain Bfgoodrich ko2 285/75r17 and 3′ lift kid icon stage that you recommended. I will do the body mount chop but im wondering if I have to get wheel spacers also. any idea?

    • Brenan - Trail4R
      Reply

      You don’t need wheel spacers. Wheel spacers will cause more rubbing with that setup.

    • Nick
      Reply

      Jorge, how did this work out for you? I am considering the same exact setup.

  • Nick Kaufman
    Reply

    Before you did this mod, did you notice the rubbing while on-road driving or just off-road driving?

    • Brenan - Trail4R
      Reply

      Both. Backing out of the driveway and reverse period, not even full lock it was rubbing hard. The 285/75R17s (33.8″) have taken some effort. I finally pulled off the rocker panel valance caps completely. I removed most of the inner fender liner on the front and rear of the wheel well. I bent the pinch welds back in as much as possible. I will eventually just cut those off. I cut the body of the 4Runner more in the front. I need to get some fiberglass fenders at some point. Now, I am figuring out how 315/70R17 (34.4″) or 35/12.50R17s (true 35″) will fit.

  • Syed
    Reply

    I am running 275/70/17 BFG All Terrain KO2s on my ’16 4Runner Limited. It also has a ProComp 3″ level kit and am planning on adding SPC UCAs to correct the caster and alignment. However, I am experiencing some rubbing on full lock turns and reversing. So will getting a body mount chop (BMC) along with fender liner trimming resolve the rubbing issues completely? Is the BMC a tough mod to do? Do you think, if I take the vehicle to a good 4×4 shop would they know exactly what to do in terms of BMC and trimming so the rubbing issues are resolved? How expensive is this process and would it be really time consuming? Would appreciate some feedback. Thanks.

    • Brenan - Trail4R
      Reply

      For the BMC, you should grab the Metal Tech 4×4 BMC kit if you are taking it to a shop that doesn’t do BMCs often. The best thing to do is drive around your house and stop as soon as you hear rubbing, make a mental note and just see where everything is rubbing. From there, you can start to make your adjustments as needed. Everyone has a different situation. No one will have your exact set-up, or at least it is rare when someone has the same set-up. Drive, listen for rubbing, hop out and check it out, make a mental note, return to the garage and start cutting. That is as basic as it gets but you get the point.

  • Rick
    Reply

    This is an awesome thread. Did you have to install bump stops with the 285/75/17 for off-roading? I really want this tire size and am willing to make the necessary cuts, but want to crush nasty trails without doing damage. I’m looking at the ridge grappler in load c that is 33.8”, I have a 2017 TRDPro with icon stage 5, and a 1” Toytec body lift.

    • Brenan - Trail4R
      Reply

      Rick, not currently running bump stops so not really “needed” for 285/75/17, but I will buy a set eventually.

  • Phillip
    Reply

    I have a 2016 with a 3” suspension lift and have a set of 17 by 9 wheel with a -6mm off set can I fit a 285/70/17 bfg k02 A/T

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