The 4 PSI Rule For Tires: What Is It, And Is It Reliable?

The 4 PSI Tire-Pressure Rule

The video explains a rule of thumb for checking whether tire pressure may have been set too low or too high. It is a maintenance guideline, not a product review.

How the Rule Works

• Check tires regularly—at least every two weeks—and use the vehicle manufacturer’s cold-pressure recommendation, usually shown on the driver-side door-jamb sticker. The number on the tire sidewall is its maximum pressure, not its normal operating pressure.
• After about 30 minutes of steady driving, check the pressure again. A rise of roughly 4 PSI is presented as typical.
• A rise substantially greater than 4 PSI may suggest the tires started underinflated; a substantially smaller rise may suggest they were overinflated.

Tire flex creates heat, which warms the air inside and raises pressure. Underinflated tires flex more and can heat up more; overinflated tires flex less and may show a smaller increase.

Supporting Guidance and Measurement

• Tire Rack’s guidance is described as allowing about 4 PSI above cold pressure for driving up to 45 mph and 6 PSI for extended highway driving.
• Priority Tire reportedly recommends adding about 4 PSI above the cold-pressure target when inflating tires while they are warm, accounting for the pressure that will fall as they cool.
• Built-in TPMS readings are generally useful for this check. A cited 2023 AAA test of 11 cars found most readings were within about 1 PSI of actual pressure.

Limitations

• The rule assumes normal tires driven at a steady speed on paved roads; it is not reliable in every situation.
• It does not apply well when tires are intentionally run at much lower pressures off-road. The video gives examples of about 12 PSI for sand, 18 PSI for mud, 20 PSI for snow, and 25 PSI for gravel.
• Tire design matters. Road tires commonly operate around 28–36 PSI, while drag slicks may operate around 4–12 PSI. A 4 PSI change is proportionally much more significant for a slick.
• Mud and off-road tires can also behave differently on pavement because their widely spaced tread blocks affect contact and heat transfer.

Verdict

The 4 PSI rule can serve as a rough diagnostic for ordinary tires in steady paved-road driving, but it should not replace the vehicle’s cold-pressure specification or be applied to off-road setups, drag slicks, or other unusual conditions.

The video gives no numerical rating. It also contains a potentially confusing statement about pressure not exceeding the cold recommendation, even though it describes normal pressure increases after driving. The cold specification is best treated as the target for cold tires.

Speaker

A single narrator presents the rule, supporting guidance, and limitations.