Should you replace one, two, or four tires?

You cannot choose a safe tire count from drivetrain alone. Check the remaining tires, the exact replacement specification, and your vehicle manufacturer's matching rules. AWD and 4WD vehicles may have specific tread-depth or circumference limits. If you do not know the applicable limit, the result is technician review required, not automatic approval for one or two tires.

This worksheet prepares that review. It is not a fitment certificate or an automatic calculator.

Record the whole set

Measure with the same unit and record the lowest relevant reading for each tire. A professional must also inspect condition; four similar numbers do not prove four safe tires.

Position	Brand and model	Full size and specification	Tread measurement	Damage or unusual wear
Front left	Fill in	Fill in	Fill in	Describe
Front right	Fill in	Fill in	Fill in	Describe
Rear left	Fill in	Fill in	Fill in	Describe
Rear right	Fill in	Fill in	Fill in	Describe
Proposed replacement	Exact model	Exact specification	Manufacturer or measured value	New or used

Also record model year, trim, drivetrain, wheel modifications, and whether front and rear fitments differ.

Use this decision sequence

1. Identify the reason for replacement. A puncture needs a repair assessment, not an automatic four-tire order.
2. Find the vehicle rule. Get the owner's manual or current manufacturer guidance for the exact vehicle.
3. Check whether matching replacements exist. A similar size from another model is not automatically an equivalent tire.
4. Compare measurements using the manufacturer's method. Do not convert tread depth into rolling circumference using an invented formula.
5. Ask the technician to approve count and placement. Keep the recommendation with the quote.

Tire Rack's AWD/4WD guidance, checked September 19, 2026, explains that manufacturers use different matching requirements. There is no universal “2/32 is always fine” rule in this worksheet.

What about putting two new tires on the front?

USTMA recommends all four together for optimal performance. Its guidance for replacing two puts the deeper-tread pair on the rear for stability; its single-replacement guidance also addresses pairing and rear placement. These are general guidelines, not permission to override a staggered fitment or a vehicle-specific requirement. USTMA replacement guidance, checked September 19, 2026.

Situation	Worksheet result
AWD, one damaged tire, manufacturer tolerance unknown	Get the applicable rule and inspection before approving quantity
Two tires selected, same-size front and rear	Ask the technician to confirm placement and remaining-tire condition
Different front and rear sizes	Preserve approved axle fitments; do not apply a blanket rotation instruction
Replacement model discontinued	Get a matching-set plan; do not substitute by size alone
All four have condition concerns	Request assessment of the complete set

What should the quote say?

Ask for the proposed quantity, exact tire models, wheel positions, the rule used to assess compatibility, and any rejected alternative. A useful answer explains why the cheaper option is unsuitable or suitable for your particular car.

For specification differences, use Can you mix tire brands?. For arithmetic, use the quote checker. Neither page replaces the technician's inspection.

Sources and review date

• www.ustires.org/tire-care-safety/replacing-tires, accessed September 19, 2026.
• www.tirerack.com/upgrade-garage/do-all-4-tires-need-to-match-on-an-allwheel-drive-or-fourwheel-drive-vehicle, accessed September 19, 2026.