All-Terrain Tyres (Tires) on Road: Trade-offs 2026

All-terrain tyres (tires) on road — at a glance

Before fitting all-terrain tyres for road driving, check that their size, load index and speed rating match what the vehicle placard specifies. On tarmac you give up some steering precision and quietness, and often some fuel economy. In return you get tougher sidewalls and grip on gravel and mud. In snow they only count as winter-capable if the sidewall shows the mountain snowflake.

💡 Calculate yours: Tyre Wear Calculator: enter your tread depth and mileage to see how quickly a set of A/T tyres is wearing.

Reading an all-terrain tyre size

All-terrain tyres use the same size code as road tyres, so a sizing mix-up is the most common mistake when switching. The code has four parts:

• The first number is the section width in millimetres
• The second number is the aspect ratio, meaning sidewall height as a percentage of the width
• R = radial construction
• The last number is the rim diameter in inches

Because the aspect ratio is a percentage of the width, a wider and a narrower tyre on the same rim do not have the same overall diameter. A change in diameter changes speedometer reading, gearing and clearance. Check any size change with the tyre size calculator before you buy, and keep the original size unless the vehicle maker lists the alternative.

P-metric, metric and LT on the sidewall

Some all-terrain tyres are made in passenger construction, and others carry an LT prefix or a load-range letter after the size. LT construction has heavier plies and a stiffer sidewall. It is more resistant to cuts on rough tracks, but it rides harder on tarmac and needs inflation pressures set from the tyre’s own load table, not the passenger figure on the door placard. If you go from passenger tyres to LT tyres, work out the pressure for your axle loads with the tyre pressure calculator. Do not copy the old number across.

Speed rating and load index on A/T tyres

Many all-terrain ranges are made with a lower speed letter than the highway tyres a 4x4 or SUV comes with from the factory. The speed letter is the last character of the size string. Letters run in order from lowest to highest speed: Q, R, S, T, H.

If the placard specifies H and the all-terrain tyre in your size is only made as S or T, that tyre does not meet the vehicle specification. Equal or higher is fine. Lower is not, and it can cause trouble at inspection and with insurers. The full letter table and the winter-tyre exception are in tyre speed ratings explained. The load index works the same way: it must be at least the figure on the placard.

Snow, ice and the mountain snowflake

Tread blocks that dig into mud and loose snow do not make a tyre a winter tyre. Two markings matter:

• M+S (mud and snow) describes the tread pattern. No snow test is needed for it, and most all-terrain tyres carry it.
• Three-peak mountain snowflake (3PMSF, “Alpine symbol”) is a performance mark. Under the Canadian Motor Vehicle Safety Regulations, as described by Transport Canada, a tyre carrying it must have passed traction testing on medium-packed snow and beaten a reference tyre. The US and Canadian standards are fully aligned.

Some all-terrain tyres carry the snowflake and some do not, so check each tyre’s sidewall rather than the product family. Even with the symbol, no standard covers ice. Transport Canada notes that Canada, the United States and the European Union have no minimum government standard for tyre performance on ice. On glare ice and cold, hard-packed roads, a dedicated winter tyre is still the stronger choice. The all-season vs winter tyres comparison covers that decision.

Provinces and territories decide whether winter tyres are required, and Quebec makes them mandatory in the winter season. Before a winter trip, check the rule for each place on your route in winter tyre laws. Where a rule is written around the snowflake symbol, an A/T tyre without it does not qualify.

Noise, fuel use and wear on tarmac

Open tread blocks hit the road one after another, and that creates a hum that rises with speed. If most of your driving is on motorways, tread noise is the trade-off you will notice most. See the tyre noise ratings guide for how to read the decibel figure where a label exists. Heavier construction and deeper, softer-moving blocks also tend to raise rolling resistance, so fuel use can go up.

Wear on tarmac depends on compound and driving style. Tall blocks can wear unevenly if rotation is skipped. On four-wheel-drive and all-wheel-drive vehicles, fit all four tyres together and rotate them on schedule. Mismatched rolling diameters between axles strain the drivetrain. Measure tread depth across the full width at each rotation, because block-edge wear and cupping show up on A/T tyres sooner than on ribbed road tyres.

Drive, keep or switch?

• Mostly tarmac, occasional gravel or a dirt road to a trailhead: a passenger-construction all-terrain tyre in the original size, with the original speed letter and load index, is a reasonable compromise.
• Regular rough tracks, sharp rocks or heavy loads: LT construction gives more protection against punctures, at the cost of ride comfort. Reset pressures from the LT load table.
• Winter in Canada, the northern US or mountain passes: choose an A/T tyre with the three-peak mountain snowflake, or keep a separate set of winter tyres if you drive on ice often.
• Mostly motorway driving with high annual mileage: a highway or all-season tyre will usually be quieter and more precise. All-terrain tyres solve a problem you may not have.
• The A/T speed letter in your size is below the placard: don’t fit it. Choose another size the vehicle maker approves, or another tyre type.

Sources

• Transport Canada, Winter Tires briefing document (Motor Vehicle Safety Regulations, snow-traction requirement and the Alpine symbol).
• Speed-rating letters as set out in UNECE Regulation 30, summarised in tyre speed ratings explained.