Tyre Load Rating for Towing: What It Means, How to Work It Out, and What Changes the Answer

Tyre load rating for towing is one of those questions that sounds simple until you try to answer it for your own car. The answer depends on the car, the conditions and how you drive, so there is no single figure that fits every driver. What this page does instead is give you the method, so you can work out your own answer and know exactly what it means.

Taking tyre load rating for towing as the case in point: The sections below take the question in order: the explanation first, then the step-by-step method, then the things that can go wrong and the signs that it is time to see a professional. Every number that depends on a place or a rule states the jurisdiction it applies to, because limits change and a figure that is right in one country can be wrong in another.

This is a calculation, not a safety approval. Always check your vehicle's door-jamb placard, load index and speed rating, and confirm fitment with a tyre professional before fitting a different tyre size.

What you need to know first — tyre load rating for towing

On this page, tyre load rating for towing is the case in point: Every tyre carries two markings that say more about its capability than the size code does: the load index and the speed rating. The load index is a number, and it maps to a maximum weight the tyre can carry — for example, a load index of 91 corresponds to 615 kilograms per tyre, 94 to 670 kilograms, 97 to 730 kilograms, 100 to 800 kilograms and 104 to 900 kilograms. The speed rating is a letter, and it maps to a maximum speed — S is 112 mph, T is 118 mph, H is 130 mph, V is 149 mph, W is 168 mph and Y is 186 mph. Both figures must match or exceed the figures on the door-jamb placard.

The useful thing about tyre load rating for towing is that it can be checked with tools most drivers already own: a gauge, a tread-depth measure and the handbook for the car.

How it works in practice — tyre load rating for towing

Taking tyre load rating for towing as the case in point: The reason both markings matter is that they describe the tyre's structural limits. A tyre with too low a load index is carrying more weight than it was built for, which builds heat and can lead to failure, and the overload may not be visible from outside. A tyre with too low a speed rating is being asked to run faster than its construction was tested for. Neither problem shows up as a warning light, which is why the markings are checked at fitting time rather than discovered on the road.

Worked example — tyre load rating for towing

On this page, tyre load rating for towing is the case in point: Take a driver covering 8,000 miles a year as an example figure. The method on this page works the same at any mileage, so the example is there to show the arithmetic, not to state a fact about your car. Start with the measurement or the figure you can check yourself — a gauge reading, a tread-depth reading, or the figure on the placard — and write it down before you do anything else. Then apply the method step by step, checking each result against the one before it, because an error early in the chain is the one that is hardest to spot later. If the result surprises you, check the inputs first: a pressure read on warm tyres, a tread depth measured in one spot only, or a figure taken from the fitted tyre instead of the placard will each give a wrong answer that looks plausible. That is why the worked example on this page states its assumptions openly, and why you should do the same with your own figures.

What changes the answer — tyre load rating for towing

For tyre load rating for towing, the point is this: XL markings add a further wrinkle. XL stands for extra load, and an XL tyre is built to carry more weight at a higher inflation pressure than a standard tyre of the same size. Fitting an XL tyre where a standard tyre was specified is usually fine, but fitting a standard tyre where an XL was specified is not, because the load capacity drops. The placard and the owner's manual say which the car needs, and the sidewall says which the tyre is.

  • On this page, tyre load rating for towing is the case in point: Load index: the number after the size, mapping to a maximum weight per tyre in kilograms.
  • Taking tyre load rating for towing as the case in point: Speed rating: the letter after the load index, mapping to a maximum rated speed.
  • On this page, tyre load rating for towing is the case in point: XL marking: extra-load construction, carrying more weight at a higher pressure than a standard tyre.
  • Placard figure: the minimum load index and speed rating the manufacturer specified for the car. That is the point this page works through for tyre load rating for towing.
  • On this page, tyre load rating for towing is the case in point: Towing and load: a car that tows or carries heavy loads needs its tyres' load rating checked with particular care.
  • Taking tyre load rating for towing as the case in point: Pressure: an XL tyre only delivers its extra load capacity at its higher rated pressure.

Common mistakes — tyre load rating for towing

  • On this page, tyre load rating for towing is the case in point: Choosing a tyre on size alone and ignoring the load index and speed rating.
  • Fitting a standard tyre where the placard specifies an XL tyre. That is the point this page works through for tyre load rating for towing.
  • For tyre load rating for towing, the point is this: Assuming a higher speed rating automatically means a better tyre for normal driving.
  • Reading the load index as a weight in kilograms instead of looking it up in the load index table. That is the point this page works through for tyre load rating for towing.

Step by step — tyre load rating for towing

  1. On this page, tyre load rating for towing is the case in point: Find the size, load index and speed rating on the door-jamb placard.
  2. Read the load index and speed rating on the sidewall of any tyre you are considering. That is the point this page works through for tyre load rating for towing.
  3. Look the load index up in the load index table to get the maximum weight per tyre. That is the point this page works through for tyre load rating for towing.
  4. For tyre load rating for towing, the point is this: Look the speed rating letter up in the speed rating table to get the maximum rated speed.
  5. For tyre load rating for towing, the point is this: Compare both figures with the placard: each must meet or exceed the specified figure.
  6. For tyre load rating for towing, the point is this: Check for an XL marking if the placard specifies extra load, and confirm the pressure the XL tyre needs.

What can go wrong, and when to see a professional — tyre load rating for towing

Most problems with tyre load rating for towing announce themselves early if you know what to look for: uneven wear, a vibration that was not there before, a warning light, a noise that changes with speed, or a reading that does not match the placard. None of these is a reason to panic, and all of them are reasons to check the basics first — pressures with a gauge when the tyres are cold, tread depth across the whole tread, and the figures on the placard rather than the ones on the fitted tyre. If the basics are right and the symptom is still there, or if you find a bulge, a deep cut, a cracked sidewall or a tyre that is losing pressure quickly, that is the point to see a tyre professional rather than to keep driving and hoping. A professional can see the inside of a tyre, measure the alignment angles and test the sensors, and those are the checks that cannot be done from the driveway. The cost of an inspection is small beside the cost of a tyre worn out early or a problem found too late.

Related guides — tyre load rating for towing

Frequently asked questions

What is a tyre load index?

For tyre load rating for towing, it is the number after the tyre size that states the maximum weight each tyre can carry. For example, 91 means 615 kilograms, 94 means 670 kilograms, 97 means 730 kilograms and 100 means 800 kilograms per tyre. The figure on your door-jamb placard is the minimum your car needs, and any replacement tyre must meet or exceed it.

What do tyre speed rating letters mean?

For tyre load rating for towing, each letter is a maximum rated speed: S is 112 mph, T is 118 mph, H is 130 mph, V is 149 mph, W is 168 mph and Y is 186 mph. The rating must match or exceed the figure on the placard. A higher rating does not by itself make a tyre better for everyday driving.

What does XL mean on a tyre?

For tyre load rating for towing, xL stands for extra load. An XL tyre is reinforced to carry more weight than a standard tyre of the same size, but only when inflated to its higher rated pressure. If your placard specifies XL, a standard tyre is not a like-for-like replacement, so check the marking before you buy.

Can I fit a tyre with a higher load index than specified for tyre load rating for towing?

For tyre load rating for towing, yes, a higher load index is acceptable, because the tyre can carry more than the minimum the car needs. What matters is that the load index is not lower than the placard figure. The same applies to the speed rating: higher is acceptable, lower is not.

Where is the load index printed?

For tyre load rating for towing, on the tyre sidewall, immediately after the size code — for example, in 205/55R16 91V, the 91 is the load index and the V is the speed rating. The placard on the driver's door frame lists the figures your car was specified with.