Before Ordering Tires: Check the Load Index, Speed Rating and XL Marking

Two tires can both say 225/45R18 and still have different load and speed specifications. If an online listing matches only the size, you have not finished the fitment check.

Before paying: compare the complete tire description with the vehicle manufacturer’s requirements and have a qualified supplier confirm suitability for your exact vehicle and use. Do not assume the tires already fitted by a previous owner are the correct reference.

1. Photograph more than the size

Record the entire sidewall description, including the numbers and letter immediately after the size, plus markings such as XL. Photograph the vehicle tire placard and identify the model year, trim and any different front/rear fitment. Bring the owner’s manual requirements to the supplier.

Michelin Canada explains that the load index and speed rating together form the tire’s service description. Tires with identical dimensions can have different service descriptions. Its guidance is to respect the vehicle manufacturer’s specified ratings, not select by diameter alone.

2. Read the load index as a code, not kilograms

The load index is a number that refers to a standardized capacity table. It does not directly state the permitted kilograms. Hankook Canada’s load-and-speed guide provides the corresponding values.

For example, load index 91 corresponds to 615 kg per tire; it does not mean 91 kg. That is a rated tire capacity under the applicable conditions, not an allowance for 615 kg of cargo in the vehicle.

If the vehicle requires a particular minimum index, do not approve a lower one because you normally drive alone. Also ask the supplier to verify the correct tire type and inflation requirements; a larger number is not a complete fitment assessment.

3. XL does not mean extra vehicle payload

XL means Extra Load. Michelin explains that these tires are reinforced to carry higher loads than standard-load tires of the same size at higher pressures. If the required specification includes XL, do not treat a same-size standard-load listing as automatically interchangeable.

Installing a tire with a higher load rating does not increase the vehicle’s permitted load. Michelin specifically cautions that the vehicle’s own limits remain. Do not add four sidewall capacities together and call the result your SUV’s payload or your pickup’s tow rating.

Ask for the complete approved specification in writing. “Fits an SUV” or “suitable for EVs” is not a substitute for confirming this vehicle’s tire requirements.

4. Treat the speed letter as a specification, not a target

Goodyear Canada explains that speed rating concerns the tire’s maximum service-speed capability under the proper conditions. It is not permission to exceed a road’s limit and does not, by itself, tell you how well the tire corners.

Replacement tires should generally meet or exceed the manufacturer’s original speed-rating requirement. If a supplier proposes a different winter specification, ask them to identify the vehicle and tire manufacturers’ applicable instructions and operating limits before accepting it. Do not downgrade based only on “I never drive that fast.”

Do not infer speed order from the alphabet or confuse the speed letter with a load-range designation. Have the supplier decode unfamiliar markings, particularly on light-truck tires or when the listing shows more than one load figure.

5. Confirm inflation separately

Transport Canada’s tire-care guidance distinguishes the vehicle’s recommended cold inflation pressure from the tire’s sidewall maximum. Do not inflate to the sidewall maximum simply because you bought XL tires.

For an approved alternative setup, ask the installer to state the correct cold pressures and any front/rear or load-related differences. Keep that information with the invoice. A load-rating explanation does not establish a new pressure for your vehicle.

Use a final quote-to-sidewall check

• Before ordering: obtain the exact brand, product, size, service description and required load/type markings—not just a photograph of the tread.
• Before installation: ask the shop to confirm that the delivered tires match the agreed specification. Resolve a substitute product before it is fitted.
• After installation: keep the invoice and record the specified cold pressures, TPMS procedure and any follow-up wheel checks the installer requires.

For wheels, sensors, mounting and seasonal costs, use our winter-tire package checklist. The service description is one important check within the complete package—not proof that wheel clearance, hardware or the rest of the fitment is correct.

Sources checked November 1, 2026. The load-index example explains the marking; it is not a tire recommendation for a particular vehicle.