[mada88]

Hello everyone,

I used to own a car with 17 inch wheels and in the owners manuel it said that 38 PSI was the best pressure for economy.

I now own a car with 15 inch wheels and I have been over inflating all 4 tyres to 38 psi.

I 38 psi optimum for fuel economy? making the tyres have more rolling resistance with a higher psi?

What is the optimum for a 15 inch tyre?

I saw a myth busters episode and they said 30 psi was best.

Or does it depend on the wheel and tyre size?

Any help is much appreciated thank you