Tire Inflation
Correct tire inflation is the single most impactful maintenance action for safety, fuel economy, and tire life. The correct pressure is found on the vehicle placard inside the driver's door jamb — never the maximum pressure molded on the tire sidewall, which is the tire's structural limit, not the vehicle's recommendation. A typical passenger car inflates front tires to 32–36 PSI and rear tires to 30–35 PSI (exact values vary by vehicle). Check pressure when tires are cold — driving heats air inside the tire and increases pressure by 4–8 PSI; a hot reading will be falsely high. Use a quality dial or digital gauge — stick gauges at gas stations are often inaccurate. Under-inflation is the most dangerous condition: a tire 25% below recommended pressure (e.g., 24 PSI when 32 PSI is specified) shows no visible flatness to the naked eye, yet runs 25% hotter, increasing the risk of sudden blowout. Under-inflated tires also suffer accelerated wear on the outer tread shoulders. Over-inflation creates excessive wear in the center of the tread, reduces the tire's contact patch and braking ability, and makes the ride harsh. Modern vehicles (2008 and later) are required to have Tire Pressure Monitoring Systems (TPMS) with dashboard warning lights, but TPMS only illuminates when pressure drops approximately 25% below specification — this is already into the danger zone. Check pressure monthly, not just when the light comes on.