# Trimming a Tacoma for Bigger Tires (Mud Flaps to Cab Mount)

Tacoma trimming ladder in order: mud flaps, fender liner, pinch weld, cab mount chop, body mount chop - which 33 or 35 triggers each step on 3rd vs 4th gen.

## Canonical URL
https://tacotires.com/guides/tacoma-trimming-bigger-tires

## Short Answer
Trim in this order: mud flaps, fender liner, pinch weld, then a cab mount chop (CMC), and a body mount chop (BMC) last. On a 3rd-gen Tacoma true 33s (285/70R17, about 32.7 in) usually need the liner and often a CMC; a 4th-gen clears 33s near bolt-on and 35s with a lift plus reversible crash-plate removal instead of a chop.

## What is the Tacoma trimming ladder, and what order do you cut in?
Fitting a bigger tire on a Tacoma is a ladder, not a single mod. You start with the easiest, most reversible change and only climb to the next rung if the tire still rubs. Each step up clears a bit more room but costs more work, more skill, and more permanence. The golden rule is to stop at the first rung that gives you clean clearance at full lock and full suspension compression - cutting more than you need just weakens the panel and hurts resale.

- Mud flap removal - the front flaps shrink the rear of the wheel well and are the first thing an oversize tire catches.
- Fender liner trim or reshape - the plastic inner liner is next; you trim the leading and trailing edges or push it back with a heat gun.
- Pinch weld roll - the folded metal lip along the rear inner arch gets rolled flat so a wide tire clears it under compression.
- Cab mount chop (CMC) - cut and re-cap the steel front cab-mount bracket that a true 33 hits at full lock; the classic 2nd/3rd-gen step.
- Body mount chop (BMC) - trim a mount farther back for very wide tires, aggressive offset, or long-travel builds; the last resort.

| Trim step | What it clears | Reversible? | Difficulty |
| --- | --- | --- | --- |
| Mud flap removal | Front tire catching the flap at the rear of the well - the first rub on almost any oversize tire | Yes, fully - the flaps bolt back on | Easy - hand tools, ~15 min |
| Fender liner trim / reshape | Rubbing on the plastic inner liner at full lock; trim the edges or heat-gun the liner back | Mostly - the liner is a replaceable part (about $50-120), but the cut one is permanent | Moderate - trim tool, heat gun |
| Pinch weld roll | The folded metal fender lip at the rear inner arch a wide tire catches under compression | Semi - metal is bent, not cut, but paint can crack and it rarely un-rolls perfectly | Moderate - fender roller or careful hammer work |
| Cab mount chop (CMC) | The steel front cab/body-mount bracket the tire hits at full lock - the classic 33 blocker on 2nd/3rd gen | No - permanent cut; a welded chop plate re-caps it | Hard - cut, grind, weld, seal, paint |
| Body mount chop (BMC) | A mount farther back, for very wide tires, aggressive poke, or long-travel suspension | No - permanent | Hard - cutting and welding |

> **Climb only as high as you have to:** Many owners fit their tire with just the first one or two rungs. Test after each step - remove the flaps, drive it, check for rub, and only move to the liner or the cab mount if the tire still contacts. There is no prize for cutting steel you did not need to touch.

## Which tire size triggers each step on a 3rd gen vs 4th gen?
The rung you land on depends mostly on tire diameter and width, your wheel offset, and your generation. The 4th-gen (2024+) wheel opening is more forgiving than the 3rd-gen (2016-2023), and Toyota moved the front cab mount rearward, so the same tire that needs a chop on a 3rd gen can be near bolt-on on a 4th gen. Width and offset matter as much as diameter: a lower-offset wheel pushes the tire outward into the liner and cab mount sooner, so a 285 that tucks on stock offset can rub hard with poke.

| Tire size (approx diameter) | 3rd gen (2016-2023) | 4th gen (2024+) |
| --- | --- | --- |
| 265/70R17 (~31.6 in) | Bolt-on, no trim | Bolt-on, no trim |
| 275/70R17 (~32.2 in) | Mud flaps, maybe minor liner | Bolt-on to mud flaps |
| 285/70R17 - true 33 (~32.7 in) | Mud flaps + liner trim, often a CMC, especially with poke or off-road flex | Near bolt-on; minor liner or bumper-tab work |
| 285/75R17 (~34 in) | Lift + liner + pinch weld + usually a CMC | Small lift + liner; reversible crash-plate removal |
| 315/70R17 (35x12.50, ~34.4 in) | Lift + CMC + more trimming - a real build | Lift + reversible crash-plate removal, no CMC |

> **A level does not add clearance where it counts:** A leveling kit (about 1.5-2 in) removes the factory rake and lifts the front at ride height, but on an independent front suspension the tire and fender travel together. At full compression the tire ends up in the same place relative to the liner and cab mount, so a level alone does not stop rub - trimming still does the work.

## Why is the cab mount chop the big step on a 3rd-gen Tacoma?
On 2nd- and 3rd-gen trucks, a boxed steel bracket - the front cab (body) mount - sits at the rear inner corner of the front wheel well. When you turn to full lock, the back edge of a 33 swings right into it. No amount of liner trimming moves that steel, so once the tire is contacting the mount, you are at the cab-mount-chop rung. A CMC cuts away the protruding corner of the bracket and welds on a formed chop plate that re-caps it, buying roughly an inch to an inch and a half of turning clearance.

This is the step most 3rd-gen owners are asking about when they say a tire almost fits. Whether you actually need it depends on the details: stock-style positive offset (about +25 to +30 mm on 3rd gen), a moderate tire, and gentle street driving sometimes squeak by on flaps and liner alone. A lower-offset or negative-offset wheel, an aggressive mud-terrain, or real trail articulation while loaded pushes most 285-on-3rd-gen builds into a CMC.

> **A CMC is permanent - do it right:** Cutting the cab mount is not reversible, so measure twice. Have it welded by someone competent, then prime, paint, and rust-proof the cut edge and the chop plate - bare steel in the wheel well rusts fast. A bolt-on chop-plate kit gives a repeatable cut line and a clean finished cap.

## How does the 4th-gen Tacoma avoid a cab mount chop?
The 2024+ Tacoma is the most tire-friendly Tacoma yet. Toyota relocated the front cab mount rearward and opened up the wheel well, so the corner that a 33 slams into on a 3rd gen is simply not in the tire's path anymore. That is why 33s are close to plug-and-play and even 35s do not require a chop - the permanent CMC that defines a big 3rd-gen build is off the table.

In its place, the 4th gen uses plastic crash plates (splash shields) low in the wheel well that a very large tire can catch. These are held by a couple of bolts per side and unbolt in minutes, freeing up roughly four inches of room. Because you are removing bolt-on plastic rather than cutting steel, this step is fully reversible - you can bolt them back for a service visit or resale. You still need a lift to run 35s for compression and up-travel clearance, and you should confirm the fit on your exact wheel and tire.

> **Reversible on 4th gen, permanent on 3rd gen:** The headline difference: a 3rd gen clears true 33s and 35s with a permanent cab mount chop, while a 4th gen clears the same tires by unbolting reversible crash plates. If keeping the truck factory for warranty or resale matters to you, that distinction is a real reason the newer platform is easier to build.

## Which trims are reversible, and which are permanent?
Reversibility drops as you climb the ladder. Knowing which rung is a point of no return helps you decide how far to go before you commit - especially on a leased or soon-to-be-sold truck.

- Fully reversible: mud flap removal (flaps bolt back on) and 4th-gen crash-plate removal (plates bolt back on). Nothing is cut.
- Mostly reversible: fender liner trimming. The liner is a replaceable part for about $50-120, so you can undo it by buying a new liner, but the one you cut is done.
- Semi-permanent: rolling the pinch weld. The metal is bent, not removed, but it rarely returns to factory shape and the paint can crack, inviting rust.
- Permanent: the cab mount chop and body mount chop. Steel is cut away and re-capped. These are structurally fine when welded and sealed correctly, but they will always show on the truck.

## How do you confirm the trim before you cut?
Every fitment answer online ends in the same caveat because it is true: rub happens at the extremes, not while the truck sits level in the driveway. The two extremes that decide whether you need the next rung are full steering lock and full suspension compression - and the worst case is both at once, while the truck is loaded. Test there before you trim, and test again after each step.

- Full lock: with the truck safely supported, turn the wheel to the stop in both directions and look and feel for contact at the liner, pinch weld, and cab mount.
- Full compression: compress each front corner - a helper bouncing the corner, or flexing over a curb or ramp - to see where the tire lands as the suspension collapses.
- Loaded and empty: do it both ways. Gear, passengers, and off-road articulation drop the truck and change where the tire sits, so an empty-driveway test can hide a rub you will find on the trail.
- Mark the contact: chalk the tire or zip-tie a few strips to the tread and drive a tight parking lot; scuffed chalk or shaved zip ties show exactly where and how hard it rubs.

> **Verify against your exact setup first:** Before buying, run your tire through a tire calculator and a max tire size estimator for your generation, and match it against owner photos on your exact trim, wheel offset, and lift. Fitment shifts with offset, wheel width, tire brand, and alignment, so treat any general answer as a starting point, not a guarantee.

## FAQ
### Do I need a cab mount chop for 33s on a 3rd-gen Tacoma?
Often, but not always. A true 33 like a 285/70R17 on a 3rd gen usually needs mud-flap removal and a fender-liner trim at minimum, and a cab mount chop once the tire hits the mount at full lock. Stock-style offset and easy street driving sometimes avoid it; a lower-offset wheel, an aggressive tire, or trail articulation while loaded usually bring it in.

### Is a cab mount chop reversible?
No. A cab mount chop cuts steel from the front body-mount bracket and welds on a chop plate, so you cannot bolt the original metal back. It is structurally sound when welded and sealed properly, but it permanently alters the truck and will show to a future buyer. That permanence is why it sits near the top of the trimming ladder, after every bolt-on step.

### What is the difference between a cab mount chop and a body mount chop?
Both cut sheet metal to clear a tire, at different spots. A cab mount chop (CMC) trims the front cab/body mount at the rear of the front wheel well, where a 33 hits at full lock. A body mount chop (BMC) addresses a mount farther back, needed mainly for very wide tires, aggressive offset, or long-travel suspension. CMC comes first on the ladder; BMC is a rarer, more extreme step.

### Do 4th-gen Tacomas need a cab mount chop for 35s?
Generally no. The 2024+ Tacoma moved the cab mount rearward, so 35s clear without cutting steel. Instead you remove the plastic crash plates - a couple of bolts per side, freeing roughly four inches - which is fully reversible. You still need a lift for the compression and up-travel clearance 35s demand, and you should confirm the fit on your exact wheel and tire at full lock and full compression.

### Can I fit 33s with just mud flap removal and a liner trim?
Sometimes, depending on generation and setup. On a 4th gen a 285/70R17 is near bolt-on. On a 3rd gen, flaps plus a liner trim clear many 33s at stock-style offset with mild driving, but hard turns while loaded or a lower-offset wheel often bring the cab mount into play. Test at full lock and full compression before deciding you are finished.

### How do I check if my tire will rub before I trim?
Cycle the suspension and steering the way real driving does. With the truck safely supported, turn to full lock both directions and check for contact, then compress each front corner while loaded. Chalk the tire or zip-tie strips to the tread and drive a tight lot - scuff marks show exactly where it rubs. Test empty and loaded, since ride height and articulation move the tire.

## Related
- [Max tire size estimator](https://tacotires.com/max-tire-size-calculator)
- [Tire size calculator](https://tacotires.com/tire-calculator)
- [33-inch tires on a stock Tacoma](https://tacotires.com/guides/33-inch-tires-on-stock-tacoma)
- [Tacoma lift kit and tire size by height](https://tacotires.com/guides/tacoma-lift-kit-tire-size-by-height)

## Sources
- [trailtacoma.com - DIY Cab Mount Chop for 2nd/3rd Gen Tacoma](https://trailtacoma.com/diy/diy-cab-mount-chop/)
- [TORQ Engineering - 4th Gen Tacoma Tire Fitment Guide (33s, 34s, 35s)](https://torq-engineering.com/blogs/leveling-kits/4th-gen-tacoma-tire-fitment-guide)