I was at the Toyota std pressure rating of 35/33 and was doing just at 49mpg in my mostly 55 to 65 mph interstate romps to work daily. I made the pressure jump to 42/40 and have these observations: 1. I dont notice any difference in ride. Seems about the same. No bone jarring uncomfortableness. Almost seems a bit quicker to control? 2. My average mpg has risen from 49 to 55 ! I can recommend this highly!