Choosing the right car tires involves more than matching the size printed on the sidewall. This checklist explains how to find your vehicle’s recommended tire pressure, read load-index and speed-rating codes, and assess whether a replacement tire or wheel-size change is appropriate for your sedan, SUV, van, or light truck.
Overview
Three specifications work together when you select tires: inflation pressure, load index, and speed rating. The vehicle manufacturer sets these requirements based on the vehicle’s weight, handling, braking, suspension, and intended use. A tire can fit the wheel and still be unsuitable if it does not meet the vehicle’s load or speed requirements.
Find the correct tire pressure first
Look for the tire-information label on the driver’s door jamb, door edge, or another location specified in the owner’s manual. It commonly lists the recommended cold pressure for the front and rear tires, the approved tire size, and sometimes a separate pressure for a temporary spare. Use this vehicle information rather than the maximum pressure molded into the tire sidewall.
The recommended pressure is normally stated for tires that are cold, meaning the vehicle has been parked long enough for the tires to return close to outdoor temperature. Driving, direct sunlight, heavy loads, and warm weather can raise the reading temporarily. Do not let air out of a warm tire simply to reach the cold-pressure number.
Understand the sidewall marking
A marking such as 225/55R17 97V contains several specifications:
- 225 is the nominal section width in millimeters.
- 55 is the aspect ratio, or sidewall height as a percentage of the width.
- R identifies radial construction.
- 17 is the wheel diameter in inches.
- 97 is the load index.
- V is the speed rating.
The size and service description must be considered together. Matching only the first four parts of the marking is not enough.
Tire load index explained
The load index is a code that corresponds to the maximum load the tire can carry when used under the conditions specified by the tire manufacturer. It is not the same as the vehicle’s total payload rating, and it should not be treated as a simple percentage or a direct weight measurement.
| Example code | Approximate maximum load per tire | Practical meaning |
|---|---|---|
| 91 | 615 kg | Common on some smaller and midsize passenger-car applications |
| 95 | 690 kg | Provides more carrying capacity than load index 91 |
| 100 | 800 kg | Often relevant to heavier passenger vehicles or SUV applications |
| 104 | 900 kg | May appear on certain larger SUV, van, or light-truck tires |
These examples are for explaining the code, not for recommending a tire for a particular vehicle. The replacement tire should meet or exceed the vehicle manufacturer’s required load index. For vans, pickups, and light trucks, also check whether the vehicle calls for a particular commercial or light-truck tire construction.
Tire speed rating chart
The speed rating is represented by a letter and indicates the tire’s rated capability under specified test conditions. It is not a target driving speed and does not make speeding safe. Common examples include:
| Rating | Rated speed | Typical interpretation |
|---|---|---|
| H | 210 km/h | Used on many passenger cars and some crossovers |
| V | 240 km/h | Common on vehicles designed for higher-speed road use |
| W | 270 km/h | Found on some performance-oriented applications |
| Y | 300 km/h | Used for certain high-performance applications |
Always follow the vehicle manufacturer’s specification and local requirements. A lower speed rating can change handling and may not be acceptable for the vehicle. If you are considering a different rating, confirm the choice with the vehicle manual, tire manufacturer, or a qualified tire professional.
Checklist by scenario
Replacing tires on a sedan
- Record the exact size, load index, and speed rating from the door label or owner’s manual.
- Confirm the recommended front and rear cold pressures; they may not be identical.
- Compare the replacement tire’s service description with the original requirement.
- Inspect all four tires for even wear, damage, and age-related cracking before deciding whether only two tires should be replaced.
If replacing only two tires, ask the installer about the safest axle placement for your vehicle and tire type. The correct arrangement can depend on drivetrain, tire condition, and manufacturer guidance.
Choosing tires for an SUV or crossover
Do not assume that an SUV needs the same pressure or load rating as a similarly sized passenger car. Check whether the label specifies a passenger-car tire or a tire with a different construction. Consider the vehicle’s usual cargo, towing use, and seating capacity, but never exceed the vehicle’s stated axle or gross-weight limits.
Checking a van
Vans can experience large changes in load between empty and fully occupied. Use the pressure guidance for the relevant load condition if the vehicle label provides one. Confirm that the tire’s load index and construction match the van’s requirement, especially when choosing replacement tires online.
Checking a light truck or pickup
Look for the complete marking, including any load-range designation, rather than relying on the load index alone. A pickup used for hauling or towing may have different recommended pressures for normal and maximum-load conditions. Follow the door label and owner’s manual, and check the trailer or towing equipment specifications separately.
Changing wheel size
When moving to a different wheel diameter, use a fitment guide to check overall diameter, width, offset, bolt pattern, clearance, and load capacity. The new tire must provide adequate load and speed ratings while maintaining suitable clearance and a practical rolling circumference. Our wheel and tire fitment guide covers these measurements in more detail.
What to double-check
- Pressure source: Use the door label or manual, not a generic pressure chart or the sidewall maximum.
- Cold condition: Measure before driving or after the vehicle has been parked long enough to cool.
- Pressure gauge: Check the gauge periodically against a known reference and use the same gauge when comparing readings.
- Valve and cap condition: Replace damaged valve components and keep caps installed to help protect the valve.
- Load index: Verify that every replacement tire meets the required minimum for the vehicle and axle.
- Speed rating: Match the required rating unless a qualified professional confirms an acceptable alternative.
- Mixed specifications: Check whether front and rear tire sizes differ and whether all-wheel-drive requirements limit mixing tires.
- TPMS: After correcting pressure or installing tires, follow the vehicle’s procedure for checking or resetting the tire-pressure monitoring system.
For further replacement planning, the tire tread depth and replacement guide can help you assess wear and visible damage. A warning light, recurring pressure loss, bulge, puncture in an unsafe repair area, or vibration deserves prompt inspection rather than repeated inflation.
Common mistakes
Using the sidewall maximum as the normal pressure. The number on the sidewall describes a tire limit under stated conditions, not necessarily the pressure your vehicle needs for everyday driving.
Choosing by size alone. Two tires with the same size marking can have different load indexes, speed ratings, constructions, and intended uses.
Ignoring different front and rear pressures. Vehicle weight distribution and handling requirements can make separate pressures necessary.
Checking pressure after a long drive. A warm reading is not directly comparable with the cold specification.
Assuming a larger wheel automatically needs more pressure. Pressure depends on the complete vehicle-and-tire application. Verify the new setup rather than applying a guess.
Forgetting the spare. Check the temporary spare’s own label or manual instructions; it may use a different pressure and speed limitation.
When to revisit
Use this checklist whenever you buy replacement car tires, change wheel size, load the vehicle for a long trip, switch between seasonal tires, or see a tire-pressure warning. Check pressure at regular maintenance intervals and before extended travel, with the tires cold.
Revisit the vehicle label and tire markings after a tire rotation, puncture repair, alignment service, or change in driving load. If pressure drops repeatedly, do not compensate indefinitely with air; have the tire, valve, wheel, and TPMS components inspected.
Before ordering tires online, save a photo of the door label and write down the complete sidewall marking. Then confirm the vehicle by make, model, year, engine or trim where relevant, and VIN when fitment is uncertain. This final step helps prevent a tire that appears to fit from being installed with the wrong capacity or rating.
For seasonal planning, review the requirements before the first major temperature change rather than waiting for a warning light. Temperature changes can affect pressure readings, while winter conditions may also influence whether a dedicated winter tire is more suitable than an all-season option. Compare that decision using the guidance in our winter tires versus all-season tires guide.
