mwiener2 Posted March 26, 2009 Share Posted March 26, 2009 My summer tires I've had as high as 52psi for dragstrip use. about 44/42 for street use and 40 for road course. I meant that 3psi over what you wanted wasn't EXTREMEly overinflated.... just a little. You'd get that much overinflation from the tire beign in the sun. My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
sooberoo Posted March 26, 2009 Share Posted March 26, 2009 On the outside chance could it be the weather? Extreme cold can affect fuel economy..... Link to comment Share on other sites More sharing options...
SuperCleanLGT Posted March 26, 2009 Author Share Posted March 26, 2009 My summer tires I've had as high as 52psi for dragstrip use. about 44/42 for street use and 40 for road course. I meant that 3psi over what you wanted wasn't EXTREMEly overinflated.... just a little. You'd get that much overinflation from the tire beign in the sun. Maybe the use of the word extreme was a bit "extreme" Link to comment Share on other sites More sharing options...
apexjapan Posted March 26, 2009 Share Posted March 26, 2009 It sounds typical. 2 main factors for this. 1) Friction. The stickier the tire, the more rolling resistance you have, the lower the gas mileage you will get. Not only that, as they get wider they lower your aerodynamic (well, increase it to be exact) profile. If you want really good gas mileage, get some bicycle tires - and don't turn (that's actually somewhat easy to do in America....). 2) Weight. The bigger/wider the tire, the more material that is being used in said tire. Short profiles have to have a lot of material in the sidewalls as well to compensate for the shortness. Couple that with naturally heavier 18" wheels, and the fact that all this mass is being pushed out further from the hub, and it's naturally going to need more hp to get them rolling. It's always an eye-opener going from a 18" "performance" setup to a 16" "daily driver" setup. Regards, Paul Hansen http://www.avoturboworld.com Link to comment Share on other sites More sharing options...
OhBe1 Posted March 26, 2009 Share Posted March 26, 2009 ...The tires are Hankook Ventus Sport K104 225/35ZR-18. The snows are Hankook Ice Bears in 205/50/17. ... For a given distance, the wheels & internals are making about 3.6% more revolutions with the summer tires. 06LOB2.5i MT, JDMRSB, GYTTs, HPS, LGT Mufflers & Leather Wheel, SubiMomo Knob, Inalfa Moonroof, Clutch Switch Bypass, DeDRLd, DeChimed, & Straight Headrest. Link to comment Share on other sites More sharing options...
SuperCleanLGT Posted March 26, 2009 Author Share Posted March 26, 2009 For a given distance, the wheels & internals are making about 3.6% more revolutions with the summer tires. Interesting... Link to comment Share on other sites More sharing options...
Underdog Posted March 26, 2009 Share Posted March 26, 2009 The OD on the tires is the same as the winter set up. I believe the weight of the new 18s is less than the stock 17s, but I have yet to find concrete documentation. Thank you, Judd Yeah, not sure how they could be the same OD... not even close by calculation: 225/35-18: (225*.35)*2 + (18*25.4) = 614.7mm Diameter 205/50-17: (205*.5)*2 + (17*25.4) = 636.8mm Diameter Winter tires are X% larger than Summer: (636.8-614.7)/614.7 = .0359 * 100 = 3.59% ~3.6% as OhBe1 stated. A 225/40-18 would have been better at 637.2mm Diameter, which would result in the Summer tires being a mere .06% off from your Winters. Of course these numbers are all theoretical, actual published rev/mile info from the manufacturer would be even more accurate. The Crimson Dynamo Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.