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-   -   MPG after new tires (http://www.jeepgarage.org/f203/mpg-after-new-tires-65618.html)

Bnesja 09-18-2013 08:42 AM

MPG after new tires
 
I just replaced the bald stock tires on my 04 Grand Cherokee with 245/70r17 General Grabber AT2s and went from about 20mpg on highway to about 15.5mpg. Is this common or am I in need of a serious tuneup?

Frango100 09-18-2013 10:40 AM

Re: MPG after new tires
 
The new tires are a bit wider then the stock ones, which will give some more resistance with the ground, but the mpg difference is too big. Did it really change directly after changing the tires?

Bnesja 09-18-2013 10:43 AM

Temperature got about 10 degrees colder outside. The tires are siped, maybe that adds a lot of resistance?

bill_de 09-18-2013 11:17 AM

Re: MPG after new tires
 
Did you check your tire pressure after the temperature dropped?


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Bnesja 09-18-2013 11:37 AM

No I haven't. They were installed when it was cooling off but they do feel loose. I'll check that out for sure! Any recommended PSI?

bill_de 09-18-2013 12:10 PM

Re: MPG after new tires
 
I figure somewhere between what it says on the door jamb and the max indicated on the tire as a starting point.


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Bnesja 09-18-2013 12:17 PM

Thank you for your help!

Bnesja 09-18-2013 01:40 PM

The door says 33 psi (cold)
The tire says 44 psi

They are inflated to about 35.5 psi each

Mikessrt 09-18-2013 01:49 PM

Re: MPG after new tires
 
Quote:

Originally Posted by Bnesja (Post 895754)
The door says 33 psi (cold)
The tire says 44 psi

They are inflated to about 35.5 psi each

35.5 cold or hot?

Bnesja 09-18-2013 01:52 PM

Cold. It's been sitting out in the parking lot all day.

bill_de 09-18-2013 02:39 PM

Re: MPG after new tires
 
That doesn't sound bad. You might try adding a couple of pounds if it doesn't adversely affect the ride.


And do that tune-up for good measure. ;)


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Bnesja 09-18-2013 02:40 PM

Thank you for all of your help.


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