Tire load index and speed rating

The two tokens after the size. Not geometry, still mandatory.

Recommended Tire Care & Emergency Gear

Protect your tire investment, prevent uneven tread wear, and stay prepared for highway roadside emergencies.

Driver Equipment
Roadside Power Roadside Must

NOCO Boost Plus GB40 1000A 12V Lithium Jump Starter

Ultra-compact 1000-amp lithium jump starter rated for gasoline engines up to 6 liters and diesels up to 3 liters. Delivers up to 20 jump starts per charge with spark-proof technology and reverse polarity safety protection.

Revives dead vehicle batteries instantly without needing a second jump car
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Emergency Air Pro Compressor

Heavy-Duty 12V Metal Cylinder Portable Tire Inflator

High-output direct battery clamp air compressor delivering up to 120 PSI. Inflates standard passenger tires and oversized SUV/truck tires (up to 33 inches) in minutes with thermal overload cutoff protection.

Eliminates roadside strandings and avoids coin-operated gas station air pumps
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Wheel Service Torque Spec

LEXIVON 1/2-Inch Drive Click Torque Wrench (10-150 ft-lb)

Pre-calibrated reversible click-stop torque wrench with electro-black finish and dual-range highlighted scale. Ensures wheel lug nuts are tightened to exact manufacturer torque specifications.

Prevents warped brake rotors, broken wheel studs, and loose lug nuts
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Pressure Calibration Driver Essential

AstroAI Heavy-Duty Digital Tire Inflator Gauge (250 PSI)

Commercial pistol-grip inflator gauge with backlit LCD, heavy-duty brass air chuck, and quick-disconnect bleeder valve. Delivers precise 0.1 PSI resolution for exact cold-pressure balancing.

Maximizes tire contact patch, fuel efficiency, and tread longevity
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Puncture Repair Flat Defense

Boulder Tools Heavy-Duty All-Metal Tire Plug Repair Kit

Heavy solid steel T-handle spiral reamer and split-eye insertion needle with self-vulcanizing rubber repair strings. Plugs nail punctures and screw holes in steel-belted radial tires without demounting wheels.

Permanently seals tread punctures on the shoulder in under 10 minutes
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Safety Inspection Wear Inspector

Digital Tire Tread Depth Gauge with Backlit LCD Screen

High-precision hardened probe gauge measuring remaining rubber depth in 32nds of an inch and millimeters. Features one-touch zero tare to detect early suspension camber wear.

Alerts you before tread wears past the critical 4/32" wet hydroplane threshold
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Tire Maintenance & Wheel Service Matrix

Standard vehicle maintenance intervals to maximize tread lifespan, fuel economy, and highway braking stability.

Service Task Recommended Equipment Service Interval Vehicle Safety & Handling Impact
Cold Pressure Calibration Digital Inflator Gauge (0.1 PSI resolution) Monthly or before highway road trips Maintains uniform footprint, avoids edge-shoulder wear, and saves fuel.
Lug Nut Torque Verification 1/2-Inch Drive Click Torque Wrench Every tire rotation or 50 miles after wheel installation Eliminates wheel wobble, sheared wheel studs, and warped brake discs.
Tread Depth Inspection Digital Tread Depth Gauge Every 3,000 miles across all 4 tires Catches toe or camber alignment issues before tires fail wet braking tests.
Roadside Puncture Sealing T-Handle Vulcanizing Plug Kit On-demand when encountering road debris Seals nail punctures in the tread crown without waiting for roadside tow trucks.
Mobile Air Delivery 12V Battery-Clamp Air Compressor Pre-trip safety and roadside emergency inflation Re-inflates low tires after slow bead leaks or temperature drops.
Emergency Powertrain Start 1000A Lithium Jump Pack Vehicle emergency glovebox standby Provides standalone cranking amps during cold morning battery drains.
Mechanic Tip
Cold Inflation Calibration Rule: Tire pressure drops roughly 1 PSI for every 10 degrees Fahrenheit drop in ambient temperature. Furthermore, driving even 1 mile generates internal friction that raises tire pressure by 3 to 5 PSI above true ambient resting level. Never set your tire pressure to the "Max PSI" molded on the tire sidewall, which indicates the maximum mechanical burst rating of the casing. Always calibrate tire pressure when the vehicle has rested for at least 3 hours, matching the cold PSI specified on the yellow-and-white driver-side door jamb placard.

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Tire load index is the number after the size, for example 116 on a 275/65R20 116T. It is pounds per tire at the inflation on the sidewall, written as a code. The letter after it is the speed rating. Neither changes diameter or width. Both change whether the tire is legal on that vehicle. This calculator ignores them on purpose. This page does not.

Load index chart

Match or exceed the door-jamb requirement. Going below is how you overload a tire that "fit fine." Extra capacity is allowed. Extra unsprung weight is a ride and mpg cost, not a free upgrade.

Tire load index, common passenger and light-truck codes.
IndexPounds per tireKilograms
841,102500
871,201545
911,356615
941,477670
951,521690
981,653750
1011,819825
1041,984900
1072,149975
1102,3371,060
1132,5351,150
1162,7561,250
1213,1971,450
1263,7481,700

Speed rating

Speed rating is the maximum sustained speed the tire is built for. S is 112 mph, T is 118, H is 130, V is 149. The full letter list lives on the tire speed rating chart. On a truck that never sees 90, a T is not a performance upgrade. Do not go below the placard letter to save money on a "same size" tire.

Load range is a third thing

LT tires also carry a load range (C, D, E, F) that describes ply rating and inflation. An E-load 275/65R20 and a P-metric 275/65R20 share a diameter and do not share a capacity. The stamp has to be read as a whole. The how to read page puts them in order.

Frequently asked questions

What is tire load index?

A code for the maximum load per tire at the sidewall inflation. 116 is 2,756 lb. Match or exceed the door-jamb number.

Can I use a higher load index than stock?

Yes. Higher is fine. Lower is not. Watch unsprung weight; a heavier LT tire is a different ride.

Does load index change the diameter?

No. Same stamp, same geometry. A heavier construction can measure a few tenths taller on the truck. That is build, not the index.