Tire Chalk Test Simulator
The gold-standard DIY method to find your exact cold tire pressure. Watch how a chalk line rubs off after driving 100 feet straight, diagnose center crowning vs shoulder wear, and lock in maximum tread life.
Interactive Tire Chalk Test Simulator
The #1 trick used by 4x4 and truck owners to find the perfect street pressure. See how chalk wear patterns immediately reveal if your tires are overinflated, underinflated, or riding on a flat contact patch.
Golden Contact Patch Found
The chalk rubbed off 100% evenly from the left shoulder to the right shoulder. The tire tread is making total flat contact with the pavement.
How to Perform the Chalk Test in 4 Simple Steps
Takes less than 10 minutes and saves hundreds of dollars in premature tire wear.
Ensure tires have rested for at least 3 hours. Set pressure to your best estimate (e.g. 38–40 PSI for 33" or 35" tires).
Draw a solid, thick chalk line straight across the tread face from shoulder to shoulder. Do it on 1 front and 1 rear tire.
Drive forward slowly in a straight line on flat asphalt. Do NOT turn the wheel, as steering scrubs the chalk off artificially!
Chalk in center only? Drop 2 PSI. Chalk on edges only? Add 2 PSI. Repeat until the line wipes away 100% clean and even.
Why the Chalk Test is Essential for 33", 35", and E-Load Tires
The Door Placard Dilemma
The tire pressure sticker on your driver's door jamb was calculated strictly for the vehicle's factory OEM tires. When you upgrade to larger 33s or 35s, or switch from a 4-ply passenger tire to a stiff 10-ply (Load Range E) all-terrain, that factory number is obsolete.
If you run factory pressure (e.g. 30–32 PSI) on a stiff LT tire, the tire may roll on its shoulders and overheat. If you run the 80 PSI maximum stamped on the tire sidewall, the center bows out like a bowling ball, ruining your ride and wearing down the middle tread in under 15,000 miles.
What the Chalk Line Reveals
A piece of standard sidewalk chalk costs $1 and gives you exact real-world data tailored to your specific truck's curb weight, aftermarket bumpers, winch, and cargo load.
When you roll forward 100 feet in a straight line, friction rubs off the chalk only where the rubber actually contacts the asphalt. If the line rubs off completely and evenly from shoulder to shoulder, you have achieved the ideal flat contact patch.
Frequently Asked Questions
Why must I drive strictly in a straight line without turning?
When you turn the steering wheel, your truck's steering geometry (Ackermann angle and camber) causes the outer tire shoulders to scrub laterally across the asphalt. This wipes off chalk from the edges even if your pressure is way too high, giving you a false reading!
Should front and rear tires have the exact same PSI?
Not always! In empty pickup trucks, the front axle carries the heavy engine, transmission, and battery, while the rear bed is completely empty. It is very common for 4x4 trucks to settle at 38 PSI in the front and 34–35 PSI in the rear for an unloaded daily commute.
Does wheel rim width affect chalk test results?
Yes! If you mount wide 12.50" tires on factory 7.5" wheels, the narrow wheel pinches the tire beads inward, causing the center of the tread to bow upward naturally. You will often need 2 to 3 PSI less air pressure on a 7.5" rim than you would on a wide 9.5" rim to get an even chalk wear line.
Calculate P-Metric to LT Load Range E PSI
Need mathematical cold PSI before drawing chalk? Use our official TRA load table calculator.