kkchoi

iTrader: (1)

I was wondering whether anyone knew whether different tire brands (i.e., Goodyear, Bridgestone, Michellin) that are similar in size have significantly different miles per gallon if the tire is set at the same PSI?

I have a 1991 Nissan 240SX and a 1999 Lexus SC400 that I switched out from Bridgestone Potenza S-03's to Goodyear Eagle F1 GS-D3's. On the Nissan, I always used to fill to 32-34 PSI on the Bridgestone's. When I got the Goodyear's, I filled at the same PSI but noticed a drastic decrease in mpg (normally 28-30 mpg on the freeway but then dropped to 20 mpg on the freeway). I changed out the O2 sensor thinking that this would solve the problem...but it didn't. I bought a new O2 sensor thinking that I may have a defective one but then I decided to increase the tire pressure to 38 PSI cold (after reading that the Goodyear Eagle's have significantly softer sidewalls). (i haven't changed out the second O2 sensor yet) Now I'm back to my usual 28 mpg.

I just got the Goodyear Eagle's (245/40 R-18 on front & 275/35 R-18 on the rears) for the Lexus so I haven't had a chance to see if my normal 25 mpg on the freeway would be affected. However, these two comparisons for the Lexus would be on different wheels (16 inch rims vs 18 inch rims) so it wouldn't be a direct (constant variable) comparison anyways.

I've previously had run-flats for the Nissan before (BF Goodrich 225/45 ZR-17 SSS) and my mpg was always in the 27-29 mpg so the (unsprung) weight probably wasn't that much of an issue. Could it be the softer more compliant sidewall of the Goodyears that affected my mpg's?

Has anyone ever heard of this before?

rominl

iTrader: (4)

it could be possible for more sticky tires i think you will need to push harder to get it rolling?

Lexusfreak

I agree & it would also depend on the many different types of tread patterns. Most auto makers put OE tires that have a very low rolling resistance (as opposed to a much more aggressive tread pattern) which improves fuel economy as they have to meet certain government standards for fuel economy (even at the expense of actual good & safe traction in bad weather conditions.......many times just heavy rain is a challenge with these types of tires I'm afraid!)