Truck and SUV Tires: Highway, All-Terrain or Mud-Terrain

Start with how you really drive

Pickups and SUVs are sold with a wide range of tires. The three broad labels you will see are highway-terrain (H/T), all-terrain (A/T) and mud-terrain (M/T). They describe a spectrum, not strict grades.

Before comparing tires, answer a few plain questions.

• How much of your driving is on pavement?
• Do you tow or haul?
• Do you see snow?
• How much noise will you put up with?

The answers matter more than the labels. This guide describes what each category generally means, then covers snow markings, LT versus P-metric tires and load, which are the parts that matter most for fit.

Highway-terrain

Highway-terrain tires are built mainly for paved roads.

Tires sold as regular passenger or light truck tires are the usual baseline when A/T and M/T tires are described below. If most of your driving is on pavement, compare specific highway tires for noise, wear and efficiency.

All-terrain

A tire guide site describes the all-terrain tread as more aggressive than a regular tire but less aggressive than a mud-terrain tire. It says A/T tires can still make some noise on the highway, but they are usually quieter than M/T tires.

The same site says A/T tires generally last longer than M/T tires, thanks to a tougher rubber compound, and generally offer better fuel efficiency. It says they usually perform better in snow than M/T tires, since a more flexible compound stays soft in cold weather.

Those are generalizations. Individual tires differ, so compare specific models and their warranty terms.

Mud-terrain

The same guide describes M/T tires as having an aggressive tread with larger blocks and more gaps, designed to grip tricky surfaces. It says they can be noisy on the highway, producing a humming or buzzing sound.

It also says M/T tires tend to wear faster than regular or A/T tires, especially if driven a lot on pavement. It adds that they are often heavier and have higher rolling resistance, which can mean lower fuel efficiency.

Mud-terrains are a fit for people who really do go off the pavement. For mostly paved use, you may be paying in noise, wear and fuel for capability you do not use.

Snow markings: M+S and the snowflake

Two markings cause confusion.

M+S stands for mud and snow. A tire retailer says it is a manufacturer-applied marking with no industry testing requirement behind it.

3PMSF is the three-peak mountain snowflake symbol, a snowflake inside a three-peaked mountain outline. The same retailer says it indicates the tire met a standardized test for traction in medium-packed snow. Another retailer says it means the tire meets certain USTMA requirements for severe snow conditions.

Some A/T tires carry the 3PMSF symbol, according to that second retailer. Check the sidewall of the exact tire you are considering rather than assuming by category.

LT or P-metric

The letters at the start of a size tell you the type of tire. Yokohama describes them this way. P-metric sizes start with the letter P. Sizes with no letter are called Euro-metric. They are dimensionally equivalent to P-metric sizes, but their load-carrying capabilities typically differ slightly. LT means a light truck metric size, meant for trucks that carry and tow more than passenger cars.

Trade press says LT tires are built more robustly than P-metric tires, to handle heavy loads under adverse conditions. It lists heavier body plies, larger bead bundles and deeper tread, with load ranges typically C, D or E.

Here is where the numbers fool people. Take two sizes that look nearly identical.

• 265/70R17
• LT265/70R17

They are different tires with different load ratings. Never mix LT and P-metric tires on one vehicle, according to that same trade article.

Federal rules also reduce a P-metric tire's load capacity when it is used on a light truck. One tire maker's technical bulletin says the reduction factor is 1.1, and that it is not needed for LT-designated tires.

So match your placard. Do not assume that two sizes with the same digits carry the same load.

Load index and load range

Load index is the number after the size that tells you how much a tire can carry. USTMA says to always replace a tire with a load index equal to or above the required index on the vehicle tire placard.

It also warns that tires from an older standard may be inadequate in some LT applications because their load capacity could be below the vehicle maker's requirement. Consult the placard and owner's manual.

Load matters most if you tow or haul. A tire retailer's guidance for oversize tires is that the wheel and tire must meet or exceed your vehicle's axle and gross vehicle weight rating needs.

Find the load index you need on the door placard, then compare it with the tires you are shopping. If you're not sure, ask a tire professional.

Reading flotation sizes

Some trucks use flotation sizes such as 33x12.50R15. These are written in inches instead of millimeters.

In a flotation size, the first number is the overall diameter in inches and the second is the width in inches. The last number is the wheel diameter in inches. Treat the first two as approximate, because actual dimensions vary by tire.

Whatever the format, confirm the size on your tire sidewall or door placard before you buy.

If you go bigger

Many truck and SUV owners consider larger tires. A tire retailer says a bigger tire travels farther per revolution, so the speedometer will read low, and that it can be necessary to recalibrate the speedometer and TPMS after installation.

The same retailer advises verifying clearance at full steering lock and full suspension compression. A tire maker's bulletin also says four-wheel and all-wheel drive vehicles need all four tires closely matched in diameter.

You can compare two sizes with our tire size calculator. It shows diameter and speedometer difference. It does not tell you whether a size is approved for your vehicle, and it says nothing about load.

Replacing two tires or four

USTMA recommends replacing all four tires at the same time. If you replace two, it says to install them on the rear axle, where the better grip helps avoid hydroplaning. Replacing a single tire, it says, can negatively affect suspension, transmission and tire treadwear.

Four-wheel and all-wheel drive vehicles call for special attention to diameter matching, so ask your shop to measure.

A short checklist

• What is the size, load index and speed rating on my door placard?
• How much of my driving is paved, and how much is off-road?
• Do I need a snow-rated tire? If so, is the 3PMSF symbol on the sidewall?
• Do I tow or haul?
• Does the shop measure diameters when I replace some tires on a four-wheel or all-wheel drive?

Start your search with the tire finder, which works from your vehicle or the size on your sidewall.