Mud-Terrain Tires — When the AT Is Not Enough

Most 4Runner owners are better served by a quality all-terrain — but if the truck spends real time in mud, on wet rock, and in deep snow, a mud-terrain is the tire that finally bites where an AT slips. This is the honest case for the MT and the case against it, with the sizes, the supporting work, and the numbers.

The wide voids and aggressive shoulder lugs of an MT clear mud and bite loose rock and sand far better than an all-terrain. On wet granite and in deep snow ruts the chunkier tread finds edges an AT rounds over. For a moderate-to-hard trail 4Runner on 33s, that traction is the difference between cleaning an obstacle and spinning.

The second thing you buy is casing. The current MTs worth running — the BFGoodrich KM3, the Nitto Trail Grappler, the Falken Wildpeak M/T01 — use three-ply sidewalls with wrapped shoulder rubber. On sharp desert rock and shale, that casing is what stops a $300 tire from becoming a trailside plug-and-pray. An all-terrain in the same size is meaningfully thinner in the sidewall, and sidewall cuts are the failure mode that ends trips.

There is no free traction, and the MT bill comes due every day you are not on a trail:

• Noise. An MT adds a constant drone above roughly 45 mph that no amount of rotation fully removes. It gets louder as the tread wears unevenly.
• Wet pavement. Fewer sipes and a stiffer compound mean longer wet stops and less warning before the tire lets go. This is the trade owners underestimate most.
• Tread life. Expect 35,000-45,000 miles from an MT against 55,000-65,000 from a good AT, and expect it to get loud in the last third.
• Fuel and acceleration. A 285/70R17 MT weighs roughly 60-70 lb against about 50 lb for an AT in the same size. Five of those is real rotating mass on a 270 hp, 278 lb-ft 4.0L, and it shows up in both mpg and braking distance.
• Cold-weather compliance. Many MTs carry an M+S marking but not the Three-Peak Mountain Snowflake. If you drive chain-control or winter-tire-required roads, confirm 3PMSF on the exact size before you commit.

If 80 percent of your miles are pavement and graded road, the value all-terrain is the smarter daily tire and the money is better spent elsewhere.

The MT decision is really a size decision, because on a 4Runner the size determines how much cutting you sign up for:

1. 285/70R17 (about 32.7 in, 11.2 in wide). The sane MT size. Clears with a leveling kit or mild lift plus fender-liner and inner-plastic trimming. A body mount chop is usually optional here.
2. 285/75R17 (about 33.8 in). This is where the truck goes to the shop. A 3 in lift plus anything taller than about 33.5 in and wider than about 11 in requires a body mount chop — cutting the outer portion of the front body mount bracket behind the front tire and welding in a fill plate — along with pushed-back and trimmed liners, trimmed rocker caps, flattened pinch welds, and mud flap removal.
3. 34 in and up. Full lift, body mount chop, extended bumpstops, and usually aftermarket upper control arms to recover caster and clearance. At this point the tire is driving the whole build.

Check backspacing before you order. The factory 17x7 at roughly +15 mm offset tucks a 285 well; going to a lower-offset aftermarket wheel pushes the tire out into the liner and the fender law in some states. The offset and backspacing guide has the math.

• Regear. The factory 5th gen ratio is 3.727. On 33s the 4.0L falls into a hole — sluggish off the line and hunting between gears. 4.56 restores near-factory feel on 33s and 4.88 suits a heavy, armored truck. See the regear guide; on an IFS truck front and rear must match.
• Five matched tires. Run a full-size matching spare, not a mismatched one. With a rear locker a mismatched spare loads the axle every mile it turns.
• Road-force balance. MT lugs are heavy and unevenly distributed. Standard spin balancing frequently leaves a 60-70 mph shimmy that gets blamed on the lift.
• Airing down. The soft, tall MT sidewall is most of what you paid for. Running 15-18 psi on the trail and re-inflating to about 32-35 psi on the road is the difference between the tire working and the tire being loud.
• Re-torque to 83 lb-ft after 50-100 miles, and rotate every 5,000 miles including the spare.

As of 2026, a set of five 285/70R17 mud-terrains from the three brands above runs roughly $1,400-1,900 for the tires plus $175-225 for road-force mounting and disposal. The 285/75R17 size lands $200-350 higher, and the body mount chop adds $300-600 at a shop unless you can weld.

Total realistic spend to put a 4Runner on 33 in MTs, including a regear, is $3,500-5,000. That number is the honest reason to be certain about the tire before you start.

Choose the mud-terrain only if mud, wet rock, and snow are your normal, then accept the noise, the wet grip, and the tread-life penalty as the price of the bite. For everything else the all-terrain is the better all-round tire. Buy the size your lift and body work actually support, regear to match, run five, and air down.

Tools required

• torque wrench
• tire shop mount/balance

Parts

Part	Vendor	Est. price
Mud-terrain tires (set of 5, 285/70R17 or 285/75R17)	BFGoodrich Mud-Terrain T/A KM3 / Nitto Trail Grappler M/T / Falken Wildpeak M/T01	~$1750
Road-force mount and balance (5 tires)	local tire shop	~$200

Sources

• Trail4Runner — running 34-inch tires on a 5th gen 4Runner
• Trail4Runner — fitting bigger tires: what to cut, chop and remove
• RCI Off Road — 4Runner off-road parts and armor

Related

• Running 33" Tires on the 5th Gen 4Runner
• Wheel Selection for the 5th Gen 4Runner
• All Toyota 4Runner guides & tools
• Browse the full DIY database

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Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.

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