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Goodyear MTRs
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=8&t=2873		 Page 1 of 1
Author:  Edwin [ Thu Oct 20, 2005 10:23 pm ]
Post subject:  Goodyear MTRs
I put Rubicon wheels w/ Goodyear MTRs on my KJ. My wife said that it started using more gas. I did'nt think it could be getting mileage that bad until I drove 200 miles round-trip to the deer lease this past weekend. I towed a 5'x10' trailer with an atv on it. I got an estimated 10 to 12 mpg. The KJ also lost power with the bigger tires. When I got back home, the tires came off.
Anyone else have problems like this?
Author:  Lesrace82 [ Thu Oct 20, 2005 10:30 pm ]
Post subject: 
they are bigger heavier tires. gonna take more energy to move them.
Author:  Steakgoddess [ Thu Oct 20, 2005 10:37 pm ]
Post subject: 
Think the trailer with an ATV had anything to do with it?

I put on MTRs in the Spring. Gas mileage only dropped 1-3 mpg.
Author:  broncsrule [ Thu Oct 20, 2005 11:29 pm ]
Post subject:  Mtr's
I run them at 38-40 psi. this makes a big diff in MPG's. Any lower mileage and power drops alot. Not as cushy ride either.
Author:  Tokyojoe [ Fri Oct 21, 2005 1:07 am ]
Post subject: 
I put mine on only for off-roading. No point in wasting the tires on the road. My ego is in check. I don't need to show them off.....at least not all of the time.

I had a base cop pull up to me this morning and ask if I was the guy that had the Rubi wheels and MTR's on my KJ. I told him yep and that he should visit our website (he owns a KJ also).
Author:  Edwin [ Fri Oct 21, 2005 7:38 am ]
Post subject: 
Steakgoddess wrote:
Think the trailer with an ATV had anything to do with it?

I put on MTRs in the Spring. Gas mileage only dropped 1-3 mpg.




The trailer probably had something to do with it, but I've pulled heavier loads with stock tires and got better mpg.
Author:  Skyjump136 [ Fri Oct 21, 2005 9:06 am ]
Post subject: 
On long trips I've gotten as low as 13 mpg just because of the wind (and that was BEFORE the MTRS). Sure they make a difference, but hauling a trailer will make a much bigger one.
Author:  Eddo [ Fri Oct 21, 2005 10:25 am ]
Post subject: 
The trailer makes a big difference. I get about 16 mpg towing a pop-up trailer verus the normal 21mpg I can squeeze sometimes. Only got about 15-16mpg going accross county with a big 5x10 trailer. Also, make sure you double check the evic by hand calculations, sometimes it can be quite off. On my cross county drive it said I was averaging about 12-13mpg when I was really getting more like 15-16mpg.
Author:  LibertyCRD [ Fri Oct 21, 2005 10:53 am ]
Post subject: 
Well my wife's 3.7L V6 only averages 16.5 mpg running around empty. With a 5x10 trailer and a several-hundred pound ATV on it I would expect hers to get around 13-14 miles per gallon. That's with ATs, stock size.

SO... I don't think your mileage is bad at all, all things considered.

Remember, MT/R tires are thick and heavy. That requires more force to turn them. They have a large block tread pattern. That increases rolling resistance. AND, they are taller than stock which adds more "leverage" and the laws of physics dictate that this will require more torque from your engine to turn them. So you have three different things working against your gas mileage there.

All things considered...I'd say your experience was dead on what any body else with your type of KJ would expect.
Author:  Liberty Titan [ Fri Oct 21, 2005 2:16 pm ]
Post subject: 
I have 245/75 Cooper STT's on my Libby and my mileage was killed after I put them on. Much more so than I had thought. Personally, I don't think the size has everything to do with it. Its the weight from the heavier tire. I can't remember the exact formula but I believe every extra lb. of weight in your tire takes 4X more energy to move...correct me if I am wrong...

I am debating selling my rubber and putting a more street friendly set on or perhaps purchasing another set of rims to put my stock rubber on so I can just switch back and forth from stock rubber to Coopers in my garage. But personally, not sure if my ego is in check cause I can't stomach driving around with my lift and stock rubber :wink:
Author:  Edwin [ Sat Oct 22, 2005 11:06 am ]
Post subject: 
Eddo wrote:
The trailer makes a big difference. I get about 16 mpg towing a pop-up trailer verus the normal 21mpg I can squeeze sometimes. Only got about 15-16mpg going accross county with a big 5x10 trailer. Also, make sure you double check the evic by hand calculations, sometimes it can be quite off. On my cross county drive it said I was averaging about 12-13mpg when I was really getting more like 15-16mpg.



I have not towed my camper with the MTRs but I have with the stock sized Liberator A/Ts and the gas mileage didn't change much.
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