Tyre load index 91 = 615kg per tyre: what Australian drivers must check
The tyre load index is a numeric code on the sidewall that maps to a maximum weight, in kilograms, that one tyre can carry under set reference conditions. Before buying replacements, check your vehicle placard or handbook and fit tyres that match or exceed the specified index, as confirmed by Nt and Australian Design Rule No. 24.
TL;DR:
- The load index is a conditional code that indicates the maximum load a tyre can carry under specific reference conditions, not an absolute number.
- Always verify your vehicle’s required load index and speed symbol on the placard or owner’s handbook before purchasing or fitting new tyres.
- Two load index numbers separated by a slash on commercial tyres represent different capacities for single and dual-wheel configurations, which are not interchangeable.
- Confirm the tyre’s rim size and width match your wheels alongside the load index to ensure safe fitment and proper wear.
- Fitting a tyre with a higher load index than specified is generally allowed, but it does not compensate for incorrect size or rim compatibility.
Table of Contents
- How to read the load index on your tyre sidewall
- Load index chart and common examples
- How to choose a replacement tyre that meets your vehicle’s requirements
- Special cases: commercial ratings and dual-wheel markings
- Practical checks, inflation and a pro tip before you fit tyres
- A note on how we approach tyre advice
- Checking tyres and booking a fitter made simpler
- FAQ
- Sources
How to read the load index on your tyre sidewall
Every tyre sidewall carries a string of numbers and letters that describes its size, construction and capacity. Take the marking 205/55R16 91V: the 205 is the width in millimetres, 55 is the aspect ratio, R16 is the rim diameter, and then come the two characters that matter most for load: 91 is the load index, and V is the speed symbol straight after it.
The load index on its own is not a kilogram figure. It is a code that corresponds to a maximum load under specific reference conditions, including correct inflation pressure, a reference speed, and whether the tyre is fitted singly or as part of a dual-wheel set. Change any of those conditions and the real-world capacity changes too, which is why practitioner guidance on tyre load and speed ratings treats the number as conditional rather than absolute.
The index and the speed symbol are always read together because they are tested as a pair. A tyre rated 91V has been verified to carry its load-index capacity up to the speeds associated with the V symbol, not beyond it. Swapping either figure for something lower than your vehicle requires, even if the other number looks fine, can leave you under-specified for normal driving.
Load index chart and common examples
Tyre manufacturers and regulators use a standardised table to convert the load index code into a kilogram figure, so you never have to guess. The table below lists some of the indices you will see most often on passenger and light SUV tyres.
These figures come from the load-index table published by NT.GOV.AU, which mirrors the values set out in Australian labelling requirements.
A worked example makes the jump from code to kilograms clearer. A tyre marked with load index 91 carries a maximum of 615 kilograms under reference conditions. On a car with four tyres at that rating, the combined tyre capacity sits around 2,460 kilograms, which needs to comfortably clear your vehicle’s gross axle weight plus a safety margin, not just match it.
If you are shopping for anything heavier than a standard passenger car, including vans or light commercial vehicles, check whether the tyre uses a single rating or separate single and dual-fitment figures. The two numbers are not interchangeable, and using the wrong one will understate or overstate what the tyre can actually carry.
How to choose a replacement tyre that meets your vehicle’s requirements
The vehicle placard, usually on the driver’s door jamb, glovebox or fuel flap, is the authoritative source for what your tyres need to carry. Your handbook repeats the same figures. Never copy a size or load index straight off your current, possibly worn, tyres without checking the placard first, because a previous owner or workshop may have fitted something non-standard.
Administrator’s Circular guidance on Australian Design Rule No. 24 confirms the placard reflects the vehicle’s normal and maximum loaded mass, and that replacement tyres generally need to match the specified size designation while meeting or exceeding the listed load index and speed symbol, unless the manufacturer states otherwise. A higher load index never excuses an incorrect tyre size or a rim that does not match your wheel’s specifications, since fitment and capacity are separate checks that both need to pass.
Run through this before you commit to a purchase:
- Read the placard or handbook for the exact size, load index and speed symbol required.
- Check the current tyre’s sidewall marking against those figures, not the other way round.
- Confirm the maximum load in kilograms stamped on the sidewall as a cross-check against the index chart.
- Check the speed symbol meets or exceeds what the manufacturer specifies.
- Confirm the replacement tyre’s rim diameter and width suit your actual wheels.
Our tyre sizes directory lets you check which sizes are available for your fitment before you commit to a purchase.
Special cases: commercial ratings and dual-wheel markings
Light commercial and heavy-duty tyres sometimes carry two load-index numbers separated by a slash, such as 121/120. The first number applies when the tyre is fitted singly, and the second applies when it is fitted as part of a dual-wheel set on the same axle. These are not interchangeable, and reading the wrong one means assuming a load capacity the tyre was never rated for in that configuration.
Technical guidance on commercial tyre markings notes that single and dual capacities for the same tyre can differ substantially, because the load each tyre carries changes depending on how many share the axle. The exact kilogram values for these two-number markings vary by tyre design and manufacturer, so always check the specific manufacturer’s technical data sheet for your tyre rather than assuming a standard conversion applies. Speed symbol and tyre construction can also shift the practical capacity on commercial applications, making manufacturer charts the safer reference point than a general table.
Practical checks, inflation and a pro tip before you fit tyres
Before fitting, stamp-check the maximum load in kilograms on the sidewall against the load-index chart figure as a quick sanity check. Confirm inflation pressure matches the placard, since load index ratings assume correct pressure and a reference speed. Under-inflation reduces a tyre’s real-world load capacity even if the printed index looks adequate on paper.
Rim size matters just as much as the tyre rating. A tyre with the right load index on the wrong rim width can still handle or wear incorrectly, so check rim compatibility alongside the load figures.
Pro Tip: If you tow or carry heavy loads regularly, talk to your vehicle maker about an approved higher-rated tyre rather than guessing based on the chart alone.
Our tyre size calculator helps you confirm fitment before you book, and verified local fitters can check the detail once the tyre arrives.
A note on how we approach tyre advice
Our approach to tyre advice starts with the placard, not the chart. Standards and government tables explain what a number means, but the placard tells you what your specific vehicle actually needs, and that order matters more than it gets credit for. Getting the load index right is a compliance and safety question first, a convenience question second.
— Areesh
Checking tyres and booking a fitter made simpler
Working out the right load index is only half the job. We built our tyre size calculator to help you confirm fitment against your vehicle’s requirements, and our search lets you find tyres by model or size with transparent, itemised pricing and no hidden fees.
Once you know what you need, you can search our tyre range, visualise the fit with our augmented reality tool, and check out in around three minutes with a same-day fitting confirmation from a local partner. If you are in Perth, you can book fitting directly, and the same applies for our Melbourne fitting service.
FAQ
What does tyre load index actually mean?
The load index is a numeric code that corresponds to the maximum kilograms one tyre can carry under set reference conditions of pressure and speed. For example, an index of 91 corresponds to 615 kilograms per tyre, according to NT.GOV.AU’s load and speed rating table.
How do I find the correct load index for my vehicle?
Check your vehicle’s placard, usually located on the door jamb, glovebox or fuel flap, or your owner’s handbook. These list the exact load index and speed symbol your manufacturer requires, and that figure overrides whatever is currently fitted.
Can I fit a tyre with a higher load index than specified?
Yes, fitting a tyre with a higher load index than the placard requires is generally permitted, as outlined in Australian Design Rule No. 24 guidance. It still needs to match the correct size designation and rim compatibility, since a higher index does not compensate for the wrong size or wheel fit.
What is the difference between load index and ply rating?
Load index is a standardised numeric code mapping directly to a kilogram capacity, while ply rating is an older system describing a tyre’s relative strength based on the number of fabric layers in its construction. Modern passenger and light commercial tyres sold under standards like ISO 4000-1:2024 are specified using load index rather than ply rating.
What do two load-index numbers like 121/120 mean?
Two numbers separated by a slash on commercial or heavy-duty tyres show separate capacities for single and dual-wheel fitment. The first number applies when the tyre is fitted alone on an axle, and the second applies when it shares the axle with another tyre in a dual set.
Sources
- Nt
- Administrator’s Circular 24-3-1 — Australian Design Rule No. 24 guidance
- ISO 4000-1:2024 | Standards Australia store