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Old 01-21-2014, 11:01 AM
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Tire size affecting mpg.???

Recently replaced OEM tires with new Continental CrossContact LX2's on recommendation from my shop guy (independent, NOT dealer...but very good.)

Moved up in size from 265/50/R20 to 275/55/R20 on his recommendation.

Have noticed a considerable drop in MPG.....from 20-21mpg highway to barely 16 mpg. Also noticed on long recent highway trip (1600mi) that my MDS very seldom engaged, even on flat terrain.

Have not yet been to dealer to have him check it out BUT could this change in tire size affected.???

Vehicle is 2011 GC Overland Summit 5.7L, 55k, purchased new and very well maintained.
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Old 01-21-2014, 07:38 PM
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Re: Tire size affecting mpg.???

Of course it will make a difference. Also if the tire is Low Rolling Resistance or not will effect it too.

The 2014 OEM 18" Tires are very good on MPG. I don't know too much about the 20's but I expect they are similar.

Not sure if Jeep used Low Rolling Resistance Tires in 2011. I don't think they did. The 2013 Dodge Dakota "Take-Off" Wheels I got had the same tire as the Jeep but were not the Low Rolling Resistance version. But they have a much higher wear rating.
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Old 01-21-2014, 09:52 PM
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Re: Tire size affecting mpg.???

Quote:
Originally Posted by kinerin View Post
Recently replaced OEM tires with new Continental CrossContact LX2's on recommendation from my shop guy (independent, NOT dealer...but very good.)

Moved up in size from 265/50/R20 to 275/55/R20 on his recommendation.

Have noticed a considerable drop in MPG.....from 20-21mpg highway to barely 16 mpg. Also noticed on long recent highway trip (1600mi) that my MDS very seldom engaged, even on flat terrain.

Have not yet been to dealer to have him check it out BUT could this change in tire size affected.???

Vehicle is 2011 GC Overland Summit 5.7L, 55k, purchased new and very well maintained.

You went from a 30.4 inch diameter tire to a 31.9 inch diameter tire. Going from 30s to 32s on my old wrangler netted a 15% loss in fuel economy. Keep in mind that you are now going further for every revolution of the drivetrain and your speedometer is now off as well. The guy has probably been sitting on those tires and saw his chance to sell them.
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Old 01-22-2014, 02:13 PM
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Re: Tire size affecting mpg.???

Are you doing your own mileage calculations or relying on the EVIC alone?

If you're just using the computer's mileage calculations, it's thrown off by the size of the tires and not showing you the true MPG with the new tires. You'll need a good month of doing your own math on a similar daily route to be able to pin it down as close as you can.

Further discussion can be found here: Gas mileage after new tires - Whine with my cheese
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Old 01-22-2014, 07:54 PM
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Re: Tire size affecting mpg.???

You're probably going to lose about 1 mpg. Not a big dealio.
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