How to Read Wheel Load Capacity Markings: Tire Load Index, Rim Stamps and Size Numbers

Wheel load capacity markings tell you the maximum weight one tire or one wheel is designed to carry. On the tire, look for the two- or three-digit number after the size code, such as the 102 in 225/65R17 102H. That number is the tire load index, and a load index chart converts it to a weight. Load index 102 means 850 kilograms (1,874 pounds) per tire. Many tires also print a plain-text line such as MAX LOAD 850 KG (1874 LBS). On the wheel itself, a load rating stamp such as MAX LOAD 2500 LBS gives the per-wheel limit for the rim. Each tire and wheel must carry at least its share of the vehicle's axle load. When a tire and wheel are mounted together, the lower of the two ratings sets the limit for that corner.

What Are Wheel Load Capacity Markings?

Wheel load capacity markings are the numbers and stamped text on a tire sidewall or a wheel (rim) that state the maximum load each component can support. You will find them in two places:

• Tire sidewall: a coded load index in the service description, often with a written maximum load in kilograms and pounds and a maximum inflation pressure.
• Wheel or rim: a wheel load rating stamp, usually cast or stamped on the back of the spokes, the hub mounting area or the inner barrel. It is written directly in pounds, kilograms or both.

Both are per-wheel load ratings. They describe what one tire or one wheel can carry, not what the whole axle or vehicle can carry.

How to Read the Numbers on the Tire Sidewall

The main tire marking combines dimensions, a ratio, a construction code, a rim size and performance ratings in one string. Using P225/65R17 102H as the example, each part means something different and uses a different unit.

Sidewall size code broken down

Marking	Type of value	Unit	Plain-language meaning
P	Tire category (optional)	None	P-metric passenger tire. LT means light truck. No letter usually means a metric (Euro-metric) tire.
225	Dimension	Millimetres	Nominal section width, measured from sidewall to sidewall on a specified measuring rim.
65	Ratio	Percent	Aspect ratio. Sidewall height is 65% of the section width.
R	Construction code	None	Radial construction.
17	Dimension	Inches	Rim diameter the tire is designed to fit.
102	Performance rating (coded)	Index number, converted to kg or lb	Tire load index: 850 kg (1,874 lb) per tire.
H	Performance rating (coded)	Letter, converted to km/h or mph	Speed symbol: rated up to 210 km/h (130 mph) under specified conditions.

The size code mixes millimetres and inches, and the aspect ratio is a percentage rather than a measurement. The load index and speed symbol are codes, not weights or speeds. You need a chart to turn them into kilograms, pounds or km/h.

Where the load index sits

The load index is the number right after the rim diameter, paired with the speed letter. Together they form the service description, such as 102H or 94V. Do not confuse it with other sidewall numbers:

• The DOT code ends in a four-digit manufacture date.
• Treadwear ratings (for example 400) are a wear comparison, not a weight.
• The maximum pressure figure is an inflation limit.

Wheel Load Rating Explained: The Tire Load Index

The tire load index is a numerical code for the maximum load one tire can carry at its specified inflation pressure. A higher index means more capacity, but the scale is not linear. Each step adds roughly 2–4% depending on where you are on the scale. Always look up the exact value instead of estimating.

Wheel load rating chart (selected load index values)

Load index	Maximum load (kg)	Maximum load (lb)
85	515	1,135
88	560	1,235
91	615	1,356
94	670	1,477
96	710	1,565
98	750	1,653
100	800	1,764
102	850	1,874
104	900	1,984
106	950	2,094
108	1,000	2,205
110	1,060	2,337
112	1,120	2,469
113	1,150	2,535
115	1,215	2,679
118	1,320	2,910
121	1,450	3,197
124	1,600	3,527

To estimate a set's total capacity, multiply the per-tire figure by the number of tires. Four tires with load index 102 can carry up to 4 × 850 kg = 3,400 kg in total. In practice, though, each axle and each corner must stay within its own limit.

How to read the MAX LOAD and MAX PRESS text

Many tires print the load capacity in words, for example: MAX LOAD 850 KG (1874 LBS) MAX PRESS 350 kPa (51 PSI).

• Maximum load matches the load index value, written in kilograms and pounds.
• Maximum pressure is the highest cold inflation pressure the tire is built for. It is not the recommended pressure for your vehicle. The recommended cold pressure is on the vehicle's tire placard, usually on the driver's door jamb, and in the owner's manual.

A tire reaches its rated load only at the inflation pressure specified for it in published load and inflation tables. If the tire is underinflated, its real load capacity is lower than the number on the sidewall.

XL, Reinforced, LT and dual load markings

• XL, Extra Load or Reinforced: a passenger tire built to carry a higher load index than a standard-load tire of the same size. It needs higher inflation pressure to reach that capacity.
• LT tires with a load range letter (C, D, E and so on): the letter describes the tire's load-carrying and pressure category. The load index still gives the actual weight.
• Two load indexes, such as 121/118 or 109/107: common on LT and commercial (C) tires. The first number is the load per tire in single fitment. The second is the lower load per tire in dual fitment, where two tires share one side of an axle. For 121/118, that is 1,450 kg (3,197 lb) single and 1,320 kg (2,910 lb) dual.

P-metric tires on light trucks and SUVs

Under US load and inflation standards, a P-metric passenger tire used on a light truck, SUV, multipurpose vehicle or trailer is derated. Its load capacity is divided by 1.10. A load index 102 P-metric tire in that use is therefore treated as about 773 kg (1,704 lb) instead of 850 kg (1,874 lb). Euro-metric tires without the P prefix follow their own tables.

How to Read a Wheel Load Rating Stamp on the Rim

A wheel load rating stamp is the manufacturer's marking of the maximum load one wheel is designed to carry. It is usually written as MAX LOAD followed by a value in pounds (LBS), kilograms (KG) or both. It is often found:

• on the back of the spokes,
• around the hub mounting face, or
• inside the barrel.

Some wheels do not show a load rating at all. In that case, ask the wheel manufacturer or check the product specifications.

Common rim markings and what they mean

Rim marking example	What it describes	Unit
17x7.5J or 7.5Jx17	Rim width (7.5) and rim diameter (17). J is the bead flange profile.	Inches
ET45 or OFFSET 45	Offset: distance from the wheel centreline to the mounting face.	Millimetres
5x114.3	Bolt pattern: 5 studs on a 114.3 mm circle.	Count × millimetres
MAX LOAD 690 KG / 1521 LBS	Per-wheel load rating.	Kilograms / pounds
MAX PSI 50 (often on trailer and steel wheels)	Maximum inflation pressure the wheel is designed for.	psi (pounds per square inch)

Only the MAX LOAD figure states load capacity. Width, offset and bolt pattern affect fitment, not how much weight the wheel can carry.

What does a wheel load rating of 2500 mean?

A wheel stamped MAX LOAD 2500 LBS is rated to carry up to 2,500 pounds, or about 1,134 kilograms, on that single wheel. It does not mean 2,500 lb per axle or per set. A set of four such wheels has a combined rating of 10,000 lb. Each corner, however, is still limited to 2,500 lb.

Here is how it combines with a tire. Suppose a load index 113 tire (2,535 lb) is mounted on a 2,500 lb wheel. That corner is limited to 2,500 lb, because the wheel is the weaker of the two. With a load index 112 tire (2,469 lb) on the same wheel, the tire becomes the limit.

Rating Units: Kilograms vs Pounds

Load ratings appear in kilograms on metric-standard markings and in pounds on US-market markings. Many tires and wheels show both.

• Kilograms to pounds: multiply by 2.2046. For example, 850 kg × 2.2046 ≈ 1,874 lb.
• Pounds to kilograms: divide by 2.2046. For example, 2,500 lb ÷ 2.2046 ≈ 1,134 kg.
• Pressure: 1 bar = 100 kPa ≈ 14.5 psi. So 350 kPa ≈ 3.5 bar ≈ 51 psi.

Convert all figures to the same unit before comparing a tire, a wheel and the vehicle's axle rating.

How to Check Whether Tires and Wheels Meet the Vehicle's Load Needs

To check a tire-and-wheel combination, compare each component's per-wheel rating with the load each corner of the vehicle must carry.

1. Find the gross axle weight rating (GAWR) for the front and rear axles. It is on the certification label, usually on the driver's door jamb, or in the owner's manual.
2. Divide each axle rating by the number of wheels on that axle. A front GAWR of 2,600 lb on two wheels means each front wheel must support up to 1,300 lb.
3. Convert the tire load index to a weight using a load index chart. Apply the P-metric derating if the tire is used on a light truck or SUV under US standards.
4. Read the wheel load rating stamp, or get the rating from the wheel maker.
5. Put all values in the same unit, kilograms or pounds.
6. Confirm that both the tire rating and the wheel rating are at least the per-wheel requirement. The lower of the two is the working limit for that corner.
7. When replacing tires, match or exceed the load index of the original equipment specification, at the vehicle's recommended inflation pressure.

How Tire Size Numbers Change Sidewall Height, Diameter and Circumference

Width, aspect ratio and rim diameter together set a tire's calculated sidewall height, overall diameter and circumference. Comparing these values shows how two size markings differ, even when the load index is the same.

Formulas for calculated tire geometry

• Sidewall height (mm) = section width (mm) × aspect ratio ÷ 100
• Overall diameter (mm) = rim diameter (in) × 25.4 + 2 × sidewall height (mm)
• Circumference (mm) = overall diameter × π (about 3.1416)
• Revolutions per kilometre ≈ 1,000,000 ÷ circumference (mm)

Worked example: 225/65R17

1. Sidewall height: 225 × 0.65 = 146.25 mm.
2. Rim diameter in millimetres: 17 × 25.4 = 431.8 mm.
3. Overall diameter: 431.8 + 2 × 146.25 = 724.3 mm (about 28.5 in).
4. Circumference: 724.3 × 3.1416 ≈ 2,275.5 mm.
5. Revolutions per kilometre: 1,000,000 ÷ 2,275.5 ≈ 439.5.

A higher aspect ratio or wider tread gives a taller sidewall. A larger rim diameter adds directly to overall diameter. When you increase rim size, keeping overall diameter similar requires a lower aspect ratio.

Size comparison table

Tire size	Sidewall height (mm)	Overall diameter (mm / in)	Circumference (mm)	Revolutions per km	Diameter vs 225/65R17
225/65R17	146.3	724.3 / 28.52	2,275.5	439.5	Reference
235/60R17	141.0	713.8 / 28.10	2,242.5	445.9	−1.4%
225/60R18	135.0	727.2 / 28.63	2,284.6	437.7	+0.4%
225/55R18	123.8	704.7 / 27.74	2,213.9	451.7	−2.7%
245/45R19	110.3	703.1 / 27.68	2,208.9	452.7	−2.9%

What a diameter difference means in practice

A smaller overall diameter means more revolutions per kilometre. A speedometer calibrated for the original size will then read higher than the true speed. A larger diameter has the opposite effect.

To estimate true speed, multiply the indicated speed by the new diameter divided by the original diameter. Replacing 225/65R17 with 225/55R18 gives a ratio of 704.7 ÷ 724.3 ≈ 0.973. At an indicated 100 km/h, the true speed is about 97.3 km/h.

Many fitment guides use a difference of about 3% in overall diameter as a rule of thumb. This is not a standard. The vehicle manufacturer's list of approved sizes takes precedence.

Size changes can also change load capacity. A lower-profile tire in a new size may carry a lower load index than the original fitment. Check the load index of any alternative size, not just its diameter.

Calculated geometry vs actual dimensions and fitment

The figures above are nominal values calculated from the size marking. A real tire's measurements can differ for several reasons:

• Rim width: section width is defined on a specific measuring rim. A narrower or wider rim changes the actual width slightly.
• Manufacturer design: tread profile and construction vary between brands and models, so two tires with the same size code can measure differently. Manufacturers publish actual dimensions in their specifications.
• Tread wear: diameter shrinks as tread wears down.
• Load and pressure: under vehicle weight, the loaded radius is smaller than half the unloaded diameter.

A matching calculated diameter also does not confirm fitment. Whether a tire and wheel actually fit depends on factors the size code does not cover:

• approved rim width range,
• wheel offset and bolt pattern,
• brake and suspension clearance,
• fender and wheel-arch clearance,
• the load and speed ratings the vehicle requires.

Use calculated geometry to compare sizes. Use the vehicle manufacturer's specifications and the tire and wheel makers' data to confirm that a combination fits and carries the required load.