33″ Tires On A 4th Gen 4runner: What Needs To Be Trimmed?

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285/70/17 4runner

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The factory tires are one of the Toyota 4runner’s weakest links when it comes to off road capability. Upgrading both the size and style of tire can make a world of difference. I’m going to share with you everything I had to trim or remove in order to fit 33″ tires on a 4th Gen 4runner.

A 285/70/17 all terrain or mud terrain tire is often considered to be on the larger side of things when it comes to these rigs. Sure, you can fit larger tires but the bigger you go, the more you’ll fight with clearance issues. A 285/70/17 seems to be a great balance between big and beefy without having to modify too much to make them work.

 

4runner 285/70/17

This size also works perfectly fine with the factory gearing, especially if you’ve been blessed with the low end torque of the 4.7L V8.

Keep in mind that different tires from different manufacturers will measure and fit differently. In the case of my personal 4runner, I’m running 285/70/17 Goodyear Duratracs on a set of 17″ Method Race Wheels Standards.

 

How big of tires can I fit on my 4runner?

If you don’t have a lift on your 4runner and want to avoid the modifications in this post, I would recommend sticking with no bigger than a 265/70/17 tire. Once you go either wider or taller, clearance issues might arise.

 

What needs to be trimmed to fit 33″+ tires on a 4th Gen 4runner

If you want to run big boy tires on your 4runner, you’re going to have to cut and trim. There’s simply no way around it. You’ll need to relocate your fender liners, trim your bumper, and possibly even have to cut your body mounts.

 

4th gen 4runner fender liner mod

4th Gen 4runner Fender Liner Mod

The first one is incredibly easy and will cost you nothing. Relocating your inner fender liners can gain you a ton of space in your wheel wells to fit bigger tires. Some people will choose to heat the plastic up with a heat gun and attempt to mold it into a different shape, but that really isn’t necessary.

All you need to do is remove the mounting bolts that connect the front of the fender liner to the bottom of the front bumper, move the liner as far forward as you like, and either find new existing holes to use or drill new ones. I drilled new ones in order to get mine to sit right where I wanted them.

You can easily gain more than 4″ of clearance just by doing this. No heat gun or replacement parts required. You can even reuse the original bolts.

 

4runner mud flap removal

Remove your mud flaps

There are obvious downsides to removing your mud flaps, but it’s a necessary evil. The original mud flaps are made of thick plastic and take up a lot of room right where it matters most. Unfortunately, they have to go.

The front flaps can be completely removed because there’s a nice solid metal panel behind them. I highly recommend screwing the bolts back into the empty holes though to avoid water and contaminants getting in there and causing rust.

 

4runner mud flap removal

The rear flaps are a bit more involved. Yes, you can remove them completely if you wish to do so. The problem is that they actually cover up a wide open section inside the rear bumper. Once they’re gone, dirt and debris can easily build up back there.

The solution is to carefully trim the “flap” portion off while keeping the plastic piece that screws into the inner fender. You might end up with a noticeable cut line that doesn’t look the greatest, but it’s far better than leaving everything exposed inside.

 

4th gen 4runner fender trimming

4th Gen 4runner Fender Trimming

This is where it gets a bit more serious. In order to fit bigger tires on your 4runner, you’re going to need to cut your front fenders a bit. The good news is that you don’t have to cut your actual metal fenders. The trimming needs to be done on the bottom corner of the front bumper.

This is great because not only is plastic much easier to trim, but you won’t have to worry about rust becoming an issue in the future. How clean this trimming looks really depends on how much effort you put into it.

For my 4runner, I chose to chop a decent amount off. My alignment specs allow me to avoid a body mount chop (more on that next) but the downside is that the wheel sits a bit more forward in the fender. I’m fine with this because I’d rather cut more of a plastic bumper than the metal frame.

As you can see, I didn’t spend a whole lot of time on mine. I’ve been meaning to come back in and clean up the edge, but you know how that goes. You can cut the bumper plastic fairly easily with side cutters, shears, or even a cutoff wheel on a Dremel tool. You may want to file down the edge after to make it look a bit cleaner.

 

4th gen 4runner body mount

4th Gen 4runner Body Mount Chop

I saved this one for last because quite frankly, you don’t want to do this unless you absolutely have to. There is a piece of the frame that comes out right behind the front wheels that the body mounts to. Depending on things like lift height, tire size, wheel offset and alignment specs, your tires might come into contact with it.

If that’s the case, you’ll need to cut a corner off of this body mount. People have been doing this for years with no ill effects and it’s generally considered to be a perfectly safe modification. There have been a few conspiracies about whether or not this will affect the crumple zones during a front end impact, but nothing has been proven so far.

This job is better left to someone with experience in cutting and welding metal. Although you can technically just make the cut and leave it open ended, that will allow contaminants to get inside. These Toyota trucks have enough problems with rusty frames on their own so they don’t need any extra help.

You can either have new plates fabricated and welded on or buy pre-cut ones like these. I would highly recommend taking this extra step if you do end up doing a body mount chop.

I was able to avoid doing a body mount chop on my 4runner mainly because of my alignment specs. I’m running quite a bit of forward caster because of my factory upper control arms which means my front wheels sit further forward in the wheel well.

I might have gotten extremely lucky with my specific setup because it seems most people need to do this in order to clear 285/70/17 tires – especially if they flex off road.

Think you know everything about your 4th Gen 4runner? Check out this article for some interesting hidden features:

 

Other things to change/modify

Aside from trimming or removing the things mentioned above, there are a few other important things that will need to be considered before running 33″ tires on your 4runner.

 

4th gen 4runner suspension lift

Suspension lift

I haven’t mentioned it until now but lifting your suspension is absolutely necessary if you want to run 285/70/17 tires. The factory suspension sits too low, especially in the front. You’ll want to aim for around 3″ of lift up front and 2″ in the rear to be able to fit bigger tires without rubbing.

A body lift can help as well, but since they’re typically only offered in 1″-1.25″ lifts, it won’t get you the clearance you need by itself. Make sure to check out this post for other things to consider before lifting your 4runner.

If all you care about is tire clearance, you don’t need to go crazy with an expensive lift kit. There are spacer lifts available that will get you the 3″/2″ height that you need without breaking the bank. Obviously they won’t perform nearly as well as a high quality suspension system but they’ll do the trick when it comes to fitting bigger tires.

 

4th gen 4runner 0 offset wheels

Wheel spacers or wheels with the right offset

If you’re running stock wheels, you’ll more than likely need a set of wheel spacers to run a 285 tire. At this width, the tire gets dangerously close to the upper control arms and might even rub. Spacing your wheels out with a set of quality spacers like these should give you the required clearance.

The other option is to swap to a set of aftermarket wheels in the right size. I run Method Race Wheels Standards on my 4runner in 17×8.5 with a 0 offset and 4.75 backspacing. This size fits absolutely perfectly. It gives you all the clearance you need and looks great too.

 

Wheel alignment

The last thing you can tweak is your alignment specs. Since you’ll be lifting your 4runner, you’ll need an alignment anyway. For me, a little bit of forward caster allowed me to avoid doing a body mount chop on mine. You don’t want to sacrifice driveability though so it’s best to stay as close to factory specs as possible.

Taking your 4runner to a shop that has off road experience to get an alignment is a good idea. They should know a few tricks to get things where they need to be and make sure your rig still drives great on the road.

 

4runner 285/70/17

Downsides to running larger tires on a 4runner

There are some cons to upgrading to larger tires. These are trade-offs that can’t be avoided, especially if you’re running 33″s tires on a 4runner. You’ll want to make sure you’re prepared for this before you make the switch.

 

Loss in fuel economy

There is no question that your MPG is going to take a dip with 285/70/17 tires. They’re taller, wider, and heavier – all of that will contribute to a loss in fuel efficiency. How much of a difference they make will depend on what engine you have and the type of driving you do.

The engine in your 4runner can make a difference in how many MPG you lose. The V8 might be a bit more forgiving while the V6 will need to work harder to get the bigger tires up to speed.

I lost close to 3 MPG with combined city/highway driving in my V8 4runner. This isn’t too drastic considering the visible difference between the factory tires and the 33’s. I noticed that the losses aren’t bad at all during highway driving, but the constant stopping/starting in the city is what really causes it to drink fuel.

I was able to regain most of the fuel economy that I lost by upgrading to a set of Doug Thorley headers and a Gibson cat back exhaust.

 

Loss in performance

Again, there’s no way around it. These tires are taller, wider, and especially heavier. Even with the V8, you’re probably going to notice that your 4runner feels slightly more sluggish. It’s not bad enough to really be a problem though. Eventually, you’ll get used to it.

A common rule is that anything 33″ and under will be fine with the factory gearing. While you might not be winning a race at every red light, your 4runner should still be more than capable of getting up to speed easily and safely. Once you step up to the 34″+ range, you might want to look into regearing.

Something I very rarely see discussed online is the effect larger, heavier tires has on your 4runner’s braking. Any time you’re adding weight or leverage on whatever is spinning, it’s going to require more effort to slow down or stop. In this case, we’re doing both.

Be prepared for this because it does indeed make a difference. Much like the performance loss, I wouldn’t consider it to be anywhere near unsafe. But it’s worth noting and definitely worth keeping in the back of your mind as you’re driving.

 

Inaccurate speedometer reading

Changing your tire size will affect your speedometer reading. It will also change your odometer and MPG rating in the dash (but that shouldn’t really be trusted anyway).

Once you upgrade to larger tires, your 4runner will be covering more ground than your gauges show. A 285/70/17 tire measures out to be roughly 32.7″ tall. That means your speedometer will be off by 3.5% vs the factory tires.

I’m sure you can get this reprogrammed but in my opinion, it isn’t a big enough change to warrant the effort. Just remember that you’re actually doing 62.1 MPH when it says you’re doing 60 MPH. In reality, most of us are just going with the flow of traffic anyways – a few extra miles per hour isn’t that big of a deal.

 

Spare tire fitment

The last downside to running larger tires on your 4runner is the fact that it might not fit in your spare tire location. Some people have reported being able to fit a 275/70/17 tire in the factory location, and others have even claimed that a worn out and deflated 285 can fit.

I’m ashamed to admit that I still have the factory spare on mine. What can I say, I’m a gambler. The factory size is completely useless in a flat tire situation on an AWD vehicle unless you want to risk blowing up your transfer case.

The solutions are to stick with a size you know will fit in the factory location, run an aftermarket spare tire carrier, or simply mount your tire in the cabin or on the roof. Or you can choose to live life on the edge like myself. Fingers crossed.

26 responses to “33″ Tires On A 4th Gen 4runner: What Needs To Be Trimmed?”

  1. TinB Avatar
    TinB

    Nice article! Question, what alignment specs do you use?

  2. Anton Avatar
    Anton

    Hi man. Good job! What do you think about 33/12.5/17 on R17x9J ET0?

  3. RayC Avatar
    RayC

    Great article. Regarding running a different tire size than your spare tire..It’s not an issue if you don’t lock your diffs or centre diff, regardless if it’s an AWD or part-time 4WD. If it were an issue, you’d be busting your drivetrain every time you turned left or right.

  4. Sloan Avatar
    Sloan

    I’m currently running stock UCA’s with a 3/2 Bilstein OME lift. I plan on running 285/70/17 with 0 offset wheels. Do you know your exact caster degree values you achieved in order to avoid a BMC?

    1. Canadian Gearhead Avatar
      Canadian Gearhead

      It was a long time ago but I remember it being a little out of spec despite still driving fine.

      -Tim

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