SUV Tire Specs: Load, Speed, and Terrain Choices

Load index: match it to your vehicle's weight

The load index is the number in the tire's service description that indicates the tire's load capacity at a given inflation pressure. Federal rules define load rating as the maximum load a tire is rated to carry for a given inflation pressure (49 CFR 571.109). A higher load index means a higher load capacity.

For an SUV, the critical weight numbers are the gross axle weight rating (GAWR) and the gross vehicle weight rating (GVWR) on the vehicle placard. The sum of the maximum load ratings of the tires on an axle must not be less than the axle's GAWR, as required by Federal Motor Vehicle Safety Standard 110. So when you replace tires, choose a load index that equals or exceeds the original equipment load index.

If you regularly haul heavy cargo or tow a trailer, consider extra-load (XL) tires. The federal standard defines an extra load tire as one designed to operate at higher loads and higher inflation pressures than a standard tire (49 CFR 571.139). You can run them at higher pressures to carry more weight, but always follow the vehicle's recommended pressures.

A common mistake is to ignore the load index and focus only on the size. For an SUV, an under-spec tire can overheat and fail under load. Check the placard on the driver's door jamb and compare the GAWR against the combined load capacity of the tires on each axle. If you use P-metric tires on a truck or SUV, remember that the load rating must be derated by a factor of 1.10 (49 CFR 571.120), so you may need a higher load index than a simple comparison suggests. For more details, see our load index and extra load tires articles.

Speed rating: match it to your driving

The speed rating is a letter that corresponds to the maximum speed at which a tire can carry its rated load. While the federal standards do not specify the speed rating code, they do require that new tires pass high-speed performance tests (49 CFR 571.109 and 571.139).

For an SUV used primarily for commuting and highway travel, a speed rating that matches or exceeds the vehicle's top speed provides a safety margin. If you often drive at sustained high speeds, choose a rating from the upper end of the scale. Replacing a tire with a lower speed rating than original can reduce high-speed durability.

Note that speed rating is not a measure of grip or tread life; it only indicates thermal endurance at speed. For heavy SUVs, a speed rating at least as high as the original equipment is a sensible baseline. Learn the specifics in our speed rating guide.

Tread type: match it to your terrain

The tread pattern is what actually contacts the road, and it determines how the tire performs on different surfaces. There are no federal definitions for "all-season" or "all-terrain," but the regulations do define snow tires. A snow tire must achieve a traction index equal to or greater than 112 in the snow traction test and be marked with the Alpine symbol (49 CFR 571.139).

For pavement-focused driving, a conventional all-season or grand-touring tire delivers a quiet ride and decent wet and dry grip. If you frequently drive on gravel or forest roads, an all-terrain tire with a more open tread pattern provides better traction and stone resistance. For deep mud or rocky terrain, a mud-terrain tire has the most aggressive tread, but it is noisier and wears faster on pavement.

If you live where winters are severe, a dedicated winter tire with the three-peak mountain snowflake mark is essential for ice and snow. All-weather tires carry the same mark but can be used year-round. Check our all-season vs all-weather and snow tire 3PMSF symbol articles for more. For specific terrain needs, explore our all-terrain, mud-terrain, and winter tire guides. Also, tread pattern types explains the differences.

Remember that a tire's capability is a balance. An aggressive tread gives off-road grip but sacrifices tread life and fuel economy on pavement. Consider your driving mix honestly before choosing.

Passenger vs. light truck tires

Most SUVs come from the factory with P-metric tires, which are designed for passenger car and multipurpose vehicle use up to a GVWR of 10,000 pounds, as defined in 49 CFR 571.110. LT (light truck) tires are also available for SUVs and are designated for use on light trucks and multipurpose vehicles (49 CFR 571.119).

The key difference is load capacity and construction. LT tires typically have higher load ratings and more plies, making them more durable for heavy loads and off-road use. However, if you choose a P-metric tire for a truck or SUV, Federal Motor Vehicle Safety Standard 120 requires that its load rating be divided by 1.10 before comparing it to the axle rating. This effectively reduces the P-metric tire's load capacity, so you need a higher load index than you might think.

For a large SUV that regularly tows or carries heavy payloads, an LT-metric tire with a load range C or E is often a better choice. For a crossover or a daily driver, a P-metric extra-load tire may be sufficient. Understand the differences by reading our P-metric vs LT and extra load articles, and learn about load range C vs E.

Putting it all together

When you are ready to buy SUV tires, start by reading the sidewall of your current tires and the placard on the driver's door jamb. Note the size, load index, and speed rating. Use an online tool or a tire professional to confirm that the replacement matches the load and speed requirements.

Then think about the terrain you cover: highway commutes, off-road trails, snow, or towing. That will narrow the tread type. Finally, compare the tire's load index and speed rating to the vehicle's requirements. The table below summarizes the typical approaches.

A good rule of thumb: if you are replacing original equipment, match or exceed the original load index and speed rating. If you are upgrading for heavier loads or off-road use, move to LT-metric construction and adjust the tread pattern accordingly.

• Check the vehicle placard for GVWR and GAWR.
• Match the load index to the axle loads, considering the 1.10 derating for P-metric tires on trucks.
• Choose a speed rating at least as high as the original equipment.
• Select a tread type based on your primary driving environment.

What to pick for your use

Questions

What is the difference between load index and load range?

Load index is a number that corresponds to a specific load capacity at a given inflation pressure. Load range is a letter (like C, E) that indicates ply rating and maximum pressure for light truck tires. Both help you match tire capacity to vehicle weight.

Can I use P-metric tires on my SUV?

Yes, if they meet the load requirements, but the load rating must be reduced by 1.10 when used on a truck or SUV, as specified in 49 CFR 571.120. You may need a higher load index than the same size P-metric tire used on a car.

Do I need winter tires on an SUV?

If you drive in severe snow, yes. Look for the Alpine symbol (3PMSF) on the sidewall, which is defined in 49 CFR 571.139. All-weather tires also carry this mark and can be used year-round.

What speed rating should I get for an SUV?

At least as high as the original equipment. A higher rating gives more safety margin at high speeds, but does not improve grip or tread life. Speed rating is about thermal endurance, not traction.

Are all-terrain tires good on pavement?

They are acceptable, but they are noisier and less fuel-efficient than highway tires. They offer better off-road grip. Consider your primary use: if you rarely leave pavement, an all-season tire is more comfortable.