Is 40 PSI Too High for Tire Pressure?

It depends: for many passenger cars, 40 PSI is higher than the recommended cold tire pressure (often 32–36 PSI), but for some SUVs, trucks, performance cars, and many EVs, 40 PSI falls within or near the manufacturer’s spec. The correct answer is on your vehicle’s door-jamb placard and in the owner’s manual; always set pressures “cold” and don’t use the tire’s sidewall maximum as your everyday target.

What Automakers Typically Recommend

Manufacturers specify a “cold” tire pressure for comfort, handling, braking, and tire life. You’ll find it on the driver’s door sticker and in the manual. Typical recommendations are around 32–35 PSI for many sedans and hatchbacks, 35–38 PSI for many crossovers and SUVs, and around 40–45 PSI for certain EVs that carry heavy batteries and prioritize efficiency (for example, several EVs, including popular models like the Tesla Model 3/Y, specify about 42 PSI cold depending on tire size and load).

The number molded on a tire’s sidewall (often 44–51 PSI for passenger tires) is a maximum cold pressure rating at maximum load—not the everyday pressure target. Running daily at or near that maximum can degrade ride and traction and accelerate uneven wear.

When 40 PSI Is Appropriate

The following scenarios illustrate when 40 PSI can be within normal practice, depending on the vehicle and its manufacturer recommendations.

• EVs and some performance models: Many electric vehicles and select performance trims specify around 40–45 PSI cold to support weight and efficiency.
• Heavier SUVs or trucks: Certain configurations, especially when lightly loaded front-to-rear, may list upper-30s to about 40 PSI on the door placard.
• High-load or highway use as specified: Some manufacturers provide higher rear-tire pressures for towing or full cargo loads; follow the placard/manual tables.
• Low-profile tires on larger wheels: Stiffer sidewalls and handling targets can push recommended pressures into the upper 30s to around 40 PSI.

If your door placard or manual calls for about 40 PSI cold, you’re within spec; stick to that value and adjust only as the manufacturer advises for load or speed conditions.

When 40 PSI Is Too High

There are also common cases where 40 PSI exceeds what the automaker recommends and may compromise performance or comfort.

• Most mainstream sedans/hatchbacks: If your placard states 32–35 PSI, inflating to 40 PSI is typically too high.
• Cold-weather swings: Setting 40 PSI in a warm garage may translate to even higher pressures on the road as tires heat up; conversely, overcompensating for winter cold can overshoot specs on milder days.
• Rough-road driving: Overinflation increases impact harshness and risk of damage on pothole-ridden routes.
• Using the sidewall max as a target: If your tire’s max is 44 PSI, everyday use at 40 PSI may be uncomfortably close unless your placard explicitly calls for it.

When in doubt, revert to the door-jamb recommendation; it’s calibrated for your vehicle’s weight distribution, suspension, and tire size.

Risks of Overinflation

Inflating beyond the manufacturer’s recommended cold pressure can have several downsides that affect safety, comfort, and tire life.

• Reduced traction and longer braking distances due to smaller contact patch.
• Harsher ride and greater susceptibility to impact damage from potholes and debris.
• Center tread wear, shortening tire life.
• Less predictable handling on wet or uneven surfaces.

These trade-offs can outweigh any small gains in fuel economy that sometimes accompany higher pressures.

How to Set the Right Pressure

Following a simple routine helps ensure you’re running the correct pressure for safety, performance, and tire longevity.

1. Find the placard: Check the driver’s door jamb or owner’s manual for the recommended cold pressures (front and rear may differ).
2. Measure “cold”: Check pressures before driving, or after the car has been parked for at least three hours; expect 2–4 PSI higher readings after driving.
3. Use a quality gauge: Digital or well-calibrated analog gauges reduce error; gas-station gauges can vary.
4. Adjust gradually: Inflate or deflate to match the placard, then recheck after a short drive to understand normal heat rise—but don’t bleed air from hot tires.
5. Account for temperature: Tire pressure shifts roughly 1 PSI for every 10°F (5.5°C) change. Recheck with large seasonal swings.
6. Match special conditions: If towing or carrying heavy loads, use any manufacturer-specified alternate pressures; otherwise, stick with the standard values.

This routine keeps you aligned with the vehicle’s engineering assumptions and avoids the pitfalls of both over- and underinflation.

Special Cases and Notes

TPMS Behavior

Most Tire Pressure Monitoring Systems warn only for underinflation (typically when pressure drops about 25% below spec). They often do not alert for overinflation, so it’s still essential to use a gauge.

Temperature and Altitude

Expect around 1 PSI change per 10°F; altitude has minimal practical effect on gauge readings because the gauge measures relative pressure. Always set pressures cold.

Spare Tires

Compact “donut” spares are designed for much higher pressures (often 60 PSI) and limited use; follow the spare’s sidewall and vehicle manual exactly.

Bottom Line

Forty PSI isn’t inherently too high—but it is for many conventional cars. Trust the door-jamb placard and set cold tire pressures accordingly. For vehicles that specify around 40–45 PSI (notably many EVs and some SUVs/performance models), 40 PSI can be appropriate. Avoid using the tire’s sidewall maximum as your target.

Summary

Whether 40 PSI is too high depends on your vehicle’s specification. Many cars call for 32–36 PSI cold, making 40 PSI excessive, while some SUVs, trucks, performance cars, and EVs legitimately specify around 40–45 PSI. Always follow the door placard, measure pressures cold, adjust for load only if the manufacturer instructs, and don’t bleed air from hot tires.

What happens if PSI is too high?

If PSI is too high, tires can experience premature and uneven wear, leading to a shorter lifespan. You’ll notice a rougher ride, a decrease in traction and control, making driving more difficult and dangerous, and an increased risk of a dangerous tire blowout. 
Impact on Your Vehicle

• Reduced Traction & Control: Overinflated tires cause the tread to distort, with the center of the tire carrying more weight and less of the tire’s surface making contact with the road. This reduces grip, especially in wet conditions, increasing the risk of skidding. 
• A Harsh, Bumpy Ride: With less give in the tire, you’ll feel every bump and imperfection in the road, leading to a significantly less comfortable ride. 
• Uneven and Faster Tire Wear: The focused pressure on the center of the tread causes it to wear down much faster than the edges, shortening the overall life of the tire. 
• Increased Risk of Blowouts: The stretched tire becomes more vulnerable to damage from potholes and other road hazards, making a blowout a real danger. 
• Light or Sensitive Steering: The less sensitive steering can feel more direct but also makes the car more susceptible to unpredictably reacting to steering inputs. 

How to Address High PSI

• Locate the Recommended PSI: Check the sticker on the driver’s side doorjamb for the manufacturer’s recommended tire pressure, which is the ideal pressure to use. 
• Use a Pressure Gauge: Check the pressure with an accurate gauge while the tires are cool. 
• Release Excess Air: Use a valve stem tool to press down on the pin inside the valve stem to release air slowly, monitoring the pressure as you go. 
• Check Regularly: Tire pressure changes with temperature, so it’s important to check your tire pressure regularly and adjust as needed. 

Is 40 PSI too much for tired?

Higher pressure generally is not dangerous, as long as you stay well below the “maximum inflation pressure.” That number is listed on each sidewall, and is much higher than your “recommended tire pressure” of 33 psi, Gary. So, in your case, I’d recommend that you put 35 or 36 psi in the tires and just leave it there.

Is it okay to put 40 PSI in tires?

No, for most cars a tire pressure of 40 psi is too high. You might find 40 psi suitable for some vehicles, especially if they’re carrying heavier loads or if the manufacturer’s recommendation is close to that figure. However, it’s generally too high for most passenger cars, which usually recommend between 30-35 psi.

At what PSI will a tire blowout?

A car tire will likely burst at pressures significantly above the maximum listed on the sidewall, often around 200 psi, although a tire can fail at lower pressures if it’s defective or experiences severe overloading and excessive heat. While a tire’s failure point is high, blowouts are often caused by underinflation, which leads to increased flexing, heat buildup, and friction, especially at highway speeds. 
Factors influencing a tire’s blowout pressure

• Tire Type and Age: Different tires (e.g., car, truck, bicycle) have vastly different pressure ratings and construction, and age and wear play a role in a tire’s ability to withstand pressure. 
• Max PSI on Sidewall: The maximum pressure listed on the tire’s sidewall is the maximum safe operating pressure, not the ultimate burst pressure. Exceeding this can increase the risk of failure. 
• Load and Overloading: A tire carrying a heavier load than it’s rated for will experience increased pressure from its own weight and is more susceptible to failure. 
• Temperature: Air expands when it heats up, so the pressure inside a tire increases significantly during highway driving, especially in hot weather. 

Causes of tire blowouts

• Underinflation: This is a common cause of blowouts because it creates excessive sidewall flexing and friction, which generates extreme heat. 
• Tire Defects: A weak spot or defect in the tire’s construction can lead to a sudden failure even under normal pressure. 
• High Speeds: Driving at high speeds for prolonged periods can cause tires to heat up and fail, especially if underinflated.