Image just for fun!
Over the years of owning a replica Cobra I found that proper tire pressure has been very topical. But I never really understood WHY until recently.
Hank Van Agen asked me the other day if I had a recommendation for tire pressure. I responded with what I have done without thinking about WHY.
So I did some digging. And here’s a great tip for determining proper tire pressure:
- The Weight-Based Rule: A common rule of thumb for kit cars/Cobras is 1 PSI for every 100 lbs of weight.
- “Chalk Test” Method: Draw a chalk line across the tire tread and drive in a straight line. If the chalk wears off in the center only, pressure is too high; if it wears off on the edges, it is too low.
- Surface Conditions: For street driving, 22–24 PSI is generally recommended for comfort. Lower pressures (e.g., 18 PSI) can be used on rough roads for better handling, while higher pressures may be used on tracks.
- Consider Tire Size: Smaller sidewalls often require slightly higher pressure, while traditional, taller 15-inch tires prefer lower pressures.
For Civilian cars, keep in mind many OEM tire pressure recommendations are based on average weight which typically includes a passenger and some weight for other items. Here’s a good video on calibrating OEM recommended tire pressures: