Recently had the oil changed and then about two weeks later put on new all-season tires. My mileage has dropped about 5-8 miles per gallon. What could cause this?
Go to a site like the TireRack.com or DiscountTires.com and look up your brand of tire. Look for the Rolling Resistance specs and compare your new tires to the old tires.
Sometimes you get "bargain" tires which are not the optional upgrades. These bargains may be undersize or smaller than your optional originals.
There are differences in width, but more important is the sidewall series.
A 70 series is larger than a 65 or 60 series. Your optional tire could have been a 70 and using a 65 will be a smaller tire if the width is the same.
Tire composition and material reflect in the rolling resistance.
Under inflation-many tire stores use less air to give the tire a better ride. Check your pressure, the label on the doorjam and raise the pressure,
usually to under 3 or 4 lbs the stated maximum on the tire.
Check air filter and any hose fittings that may have been disturbed by the oil change. Temperature, gasoline, and driving habits can affect gas mileage. Sometimes a locking gas cap helps too.
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Okay I will share a new tip with you that I only recently found out myself,and I am 56 years old,beenaround and fixin cars since I was 8..now, follow me here, since new tires need break-in time, check the air pressure every couple of days, with the seesaw temps we get these new tires will act funny and look low especially on cast aluminum wheels..now my friend just got a new car, a 2010 jeep with aluminum wheels and its got these 17 inch rims on it..when we picked it up we noticed a low pressure light on on the dash and we found a safety pin in one of the tires, the dealer fixed the tire(put a new one on), and used helium to inflate it to pressure because this doesnt react like regular station pressure does..I found this very fascinating..now since new tires were put on the car, you may need the emissions recalibrated by the dealer to adjust for the difference in the tire size..up to an inch in circumfrence will affect the fuel economy especially when you are used to 40-50 miles a gallon...good luck
Did you put the same size tires on or were they a smaller size. more revolutions of tires would take more fuel.
SOURCE: Maintenance Required message on. Purchased
this light can come on even thought service is not actually due. if the service was performed and the light was not on at the time, sometimes you cannot reset them if they are not actually lit, or 99% of the time the technician forgets if the light was not on. stop by your shop and they can reset it for you in just a few moments, and for no charge. good luck!
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Thanks for the posts.
Same size tires. Put on Michelin All Season that I've used many years and they used helium or is it nitrogen(?). Recalibrating may be a possibility, but I'd hate to think that it's required each time you put on a set of tires. I'll check the tire resistance, but Michelin usually tops the rankings.
The other puzz;ing thing is the amount of change. From 27/28 MPG to 19/20. That's significant!
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