Every tire sidewall carries a small set of numbers and letters that most drivers ignore. One of those numbers — the load index — decides whether your tires can safely carry the weight of your car, your passengers, your cargo, and everything else you load up before a road trip. Pick a load index that’s too low, and you’re rolling on tires that can fail under stress. Pick one that matches your vehicle’s needs, and you’ve eliminated a hidden safety risk most owners never think about.
This guide walks through how to read the load index, what the numbers actually mean in pounds and kilograms, how the rating works for the vehicle as a whole, and the common mistakes that lead body shops and tire installers to flag fitments as unsafe.
What Is Tire Load Index
The tire load index is a numerical code, usually two or three digits, that corresponds to the maximum weight a single tire can carry when properly inflated to its rated pressure. The code is part of the service description printed on the sidewall, right after the tire size and right before the speed rating letter.
A passenger-car tire marked 225/65R17 102H tells you four things in sequence: 225 mm section width, 65% aspect ratio, 17-inch rim diameter, then the service description — load index 102, speed rating H. The 102 is the load index. Look it up on a standard chart and it maps to 1,874 lbs (850 kg) per tire.
The number is not the weight itself. It’s an index that points to a value in a lookup table standardized across the industry (ETRTO in Europe, TRA in North America). The chart runs from about 0 to 279 for passenger and light-truck applications, with each step representing a small but defined increase in capacity.
Where to Find the Load Index on Your Tire
Look at the outer sidewall of any modern tire. The service description appears after the size designation:
- P225/65R17 102H — passenger-car tire, load index 102
- LT265/70R17 121/118R — light-truck tire, dual rating (121 single, 118 dual rear axle)
- 235/45ZR18 98W XL — extra-load passenger tire, load index 98
Light-truck tires often carry two load indices separated by a slash. The first number applies when the tire runs as a single (front axle or single rear). The second applies when the tire runs in a dual-rear configuration, where the load gets shared with a partner tire. The dual rating is always slightly lower because side-by-side flex changes the heat profile.
Reading the Load Index Chart
The full chart is long, but most passenger vehicles fall between load index 88 and 116. Here’s a working reference for the range you’ll actually encounter:
| Load Index | Capacity (lbs) | Capacity (kg) | Typical Use |
|---|---|---|---|
| 85 | 1,135 | 515 | Compact car |
| 88 | 1,235 | 560 | Compact / midsize sedan |
| 91 | 1,356 | 615 | Midsize sedan |
| 94 | 1,477 | 670 | Midsize sedan / small SUV |
| 97 | 1,609 | 730 | Midsize SUV |
| 100 | 1,764 | 800 | Midsize SUV / minivan |
| 103 | 1,929 | 875 | Full-size SUV |
| 106 | 2,094 | 950 | Full-size SUV / half-ton truck |
| 110 | 2,337 | 1,060 | Half-ton truck |
| 113 | 2,535 | 1,150 | Three-quarter-ton truck |
| 116 | 2,756 | 1,250 | One-ton / heavy-duty truck |
Each step up the chart adds roughly 4 to 5 percent more capacity. Going from 100 to 105 isn’t a small change — it’s an extra 396 lbs per tire, or 1,584 lbs across all four corners.
Why Load Index Matters for Safety
An under-rated tire doesn’t just wear faster. It runs hotter, and heat is the enemy of every rubber compound. Over-loading a tire above its rated capacity does three things at once: it deflects the sidewall more, raises the internal temperature beyond the design envelope, and accelerates belt separation. The failure mode is usually a tread peel or a blowout, both of which tend to happen at highway speed when the heat has built up over miles of driving.
The flip side is also worth flagging. A tire rated well above what your vehicle needs isn’t dangerous, but the extra capacity comes with stiffer sidewalls and a harsher ride. Over-rating is common when owners install light-truck tires on a half-ton truck that doesn’t actually need that capacity — they trade comfort for a margin they’ll never use.
Calculating Total Load Capacity for Your Vehicle
The math is straightforward. Multiply the per-tire capacity by four, and compare against the vehicle’s Gross Vehicle Weight Rating (GVWR), found on the door-jamb sticker.
Example: a Toyota Camry rolling on 215/55R17 94V tires. Load index 94 = 1,477 lbs per tire. Four tires = 5,908 lbs of total capacity. The Camry’s GVWR is around 4,400 lbs. That gives a comfortable margin of roughly 1,500 lbs, which is what the OEM designed in.
Example: an F-150 with 275/65R18 116T tires. Load index 116 = 2,756 lbs per tire. Four tires = 11,024 lbs of total capacity. The F-150’s GVWR sits around 7,000 lbs. Again, a wide margin — appropriate for a truck that may be loaded with cargo, towing a trailer with tongue weight, or carrying passengers near the maximum payload.
The OEM-recommended load index is always printed on the door-jamb sticker alongside the tire size. Treat that number as the floor, not a suggestion.
Load Index vs. Load Range
These two terms get used interchangeably, but they describe different things.
Load index is the numerical code on the service description. It maps to a specific weight capacity at a specific inflation pressure.
Load range is an older letter-based system (B, C, D, E, F) used mainly on light-truck and trailer tires. Each letter corresponds to a ply rating and a maximum inflation pressure. Load range C handles 50 psi max, load range D handles 65 psi, load range E handles 80 psi, and so on. A higher load range means stiffer construction and the ability to run higher pressure, which in turn allows a higher load index.
Both ratings appear together on most light-truck tires. A typical LT265/70R17 might be marked 121/118R Load Range E — load indices 121 and 118 (single / dual), and a load range that allows 80 psi cold inflation.
XL, RF, and Extra Load Markings
Passenger tires sometimes carry an XL or RF marking after the service description. These mean “extra load” or “reinforced” — the tire is built to handle a higher load index than a standard passenger tire of the same size, by running at a higher maximum pressure (typically 41 psi instead of 35 psi).
An XL tire and a standard tire might share the same physical dimensions but have different load indices. A 225/45R17 91W is a standard tire. A 225/45R17 94W XL is the reinforced version. Many modern sedans, especially European models with run-flat options or larger wheels, call for XL tires from the factory.
Installing a non-XL tire where the OEM spec calls for XL is one of the most common under-rating mistakes. Always cross-check the door-jamb sticker.
Speed Rating and Load Index Together
The load index is followed by a single letter — the speed rating. The two ratings are independent in theory but linked in practice, because manufacturers tune the construction of a tire to handle a specific combination of speed and load.
Speed ratings most drivers encounter:
- S — 112 mph
- T — 118 mph
- H — 130 mph
- V — 149 mph
- W — 168 mph
- Y — 186 mph
Downgrading the speed rating to gain load capacity, or upgrading it at the cost of load capacity, almost always means the tire is being used outside its design intent. Stick with the combined rating the OEM specifies.
Common Mistakes Body Shops and Owners Make
From years of seeing wheel-and-tire combinations come through for inspection and acquisition, a handful of load-index mistakes show up repeatedly.
Mismatched fronts and rears. Some owners replace just two tires at a time and end up with different load indices front to back. The vehicle handles unpredictably under load because the deflection profile changes between axles.
Under-rated replacements after a plus-size wheel swap. Going from a 17-inch to a 20-inch wheel on the same vehicle means a lower-profile tire. The new tire often has a smaller load index because the sidewall is shorter. If the replacement isn’t carefully cross-referenced against the door-jamb sticker, the new combination can fall below the OEM-rated capacity.
Confusion with passenger tires on light trucks. Bolting passenger-car tires onto a half-ton truck to soften the ride is a common move. The catch is that passenger tires on a light truck must have their load capacity de-rated by a factor of 1.10 — meaning you need a higher load index to match what a light-truck tire of the same nominal capacity would provide.
Ignoring trailer tire markings. ST-designated trailer tires use their own load index system and are not interchangeable with passenger or light-truck tires, even when the size looks identical.
How to Choose the Right Load Index When Buying Tires
Three steps cover most situations:
- Read the door-jamb sticker. Note the OEM-recommended tire size, load index, and speed rating. This is the floor.
- Match or exceed the load index. A higher load index is fine. A lower load index is not. Never accept “close enough” — even one number lower means hundreds of pounds less capacity across four tires.
- Cross-check inflation pressure. The load index is rated at a specific pressure. If you run a higher load index tire at a lower pressure than rated, you lose the extra capacity you paid for.
If you’re replacing tires after a wheel swap — new aftermarket rims, plus-size diameter, different offset — the tire size changes, and the load index needs to be reconsidered from scratch. The original door-jamb spec is a reference point, but the new tire-and-wheel combination has to be evaluated against the vehicle’s GVWR independently.
Tire Load Index FAQ
What load index do I need for my truck?
Check the driver-side door-jamb sticker for the OEM-recommended load index. Half-ton trucks typically need load index 110 to 116. Three-quarter-ton and one-ton trucks usually run load index 121 or higher, often paired with load range E construction.
Can I install a tire with a higher load index than recommended?
Yes. A higher load index is safe and gives you a larger margin. The trade-off is a slightly stiffer ride because higher-capacity tires generally have reinforced sidewalls.
What happens if I install a tire with a lower load index?
The tire runs hotter under normal loads, wears faster, and has a smaller safety margin before failure. Most state vehicle inspections will fail a tire that falls below the OEM-rated load index. Insurance claims after a blowout can also be affected if the tire was under-rated.
Does the load index apply at any pressure?
No. The load index assumes the tire is inflated to its rated cold pressure. Running a tire below the rated pressure reduces its actual load capacity, sometimes by 20 percent or more. This is why proper inflation matters so much for towing and hauling.
How is the load index different on light-truck tires?
Light-truck tires carry two load indices — one for single use, one for dual-rear use. The dual rating is always lower because side-by-side flex affects heat dissipation. Passenger tires only carry a single load index.
What is the maximum load index for a passenger car?
Standard passenger tires top out around load index 110 to 116 in extra-load configurations. Beyond that, you’re in light-truck or commercial territory, where the construction differs.
Why Load Index Matters for Wheel Buyers and Sellers
If you’re swapping wheels, selling a vehicle, or running a body shop that processes wheel-and-tire combinations, the load index is one of the first things to verify. A wheel-and-tire package that doesn’t match the vehicle’s GVWR is a liability for both buyer and seller. Santa Ana Wheel has been working with OEM wheels and OE-fitment tires since 1958, and load index mismatches are something we flag on every set that comes through our 47,000+ wheel inventory pipeline.
Have wheels or wheel-and-tire sets to move? Text 949-478-2033 with your year, make, model, and location. We accept payment by check or Zelle, and we handle the load-rating verification before any deal closes — so you don’t end up shipping a set that fails inspection on the receiving end.
