how much mpg can you really lose or gain because of unspung weight?
10-06-2011, 10:35 AM
#11
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No Jeep yet but on my Ford Raptor my mileage improved as did acceleration and braking. Only change I made was changing the factory cast wheels to forged wheels. I dropped 11 lbs per wheel. I reinstalled the factory 315-70-17 BFG A/T's. I gained just over 1 mpg and dropped .10 second on the 0-60 time. For the MPG test I ran a 100 mile loop before and then the same loop after. For the 0-60 times I used a G-meter and did an average of 5 runs before and after. The truck weighs right at 6000 lbs and has the factory 4.10 gears.
Keep in mind that not only are you dealing with unsprung weight but you are also dealing with rotational mass. Wheels & tires are the best place to save weight.
Keep in mind that not only are you dealing with unsprung weight but you are also dealing with rotational mass. Wheels & tires are the best place to save weight.
10-06-2011, 10:44 AM
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definitely, this topic is very complicated and probably impossible scale, there are some many factors and variables to consider, i stepped into a mess with searches about unsprung weight and rotation mass with respect to mpg. If i do go though with the tire and wheel swap i would hope to achieve 2 mpg + but with these jeeps i would not hold my breath. especially the way i drive
10-06-2011, 10:51 AM
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I went from toyo mts (very heavy) to duratracs both about same size. The toyos weighed a lot more, not certain the exact diff but I thought it was 15-20lbs. My mileage didn't change. In fact my best mileage since lift and tires happened with the toyos a few weeks before I bought the duratracs. I was expecting the reduction in weight to have a more noticeable effect.
10-06-2011, 02:04 PM
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This is the reason I went with 15" alloys and BFG KM2 35x12.50 because they only weigh a few pounds more than the stock rubi tires a wheels I had. In my case I saved weight by getting 15" rim vs 17" rim, also BFG KM2 are available in a C load rating in that size.
After I got the lift and tires on and adjusted my speedo, I only lost about 1mpg. I still get 18~20 HWY and 16~18 city
.
After I got the lift and tires on and adjusted my speedo, I only lost about 1mpg. I still get 18~20 HWY and 16~18 city
.
10-06-2011, 02:42 PM
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This is the reason I went with 15" alloys and BFG KM2 35x12.50 because they only weigh a few pounds more than the stock rubi tires a wheels I had. In my case I saved weight by getting 15" rim vs 17" rim, also BFG KM2 are available in a C load rating in that size.
After I got the lift and tires on and adjusted my speedo, I only lost about 1mpg. I still get 18~20 HWY and 16~18 city.
After I got the lift and tires on and adjusted my speedo, I only lost about 1mpg. I still get 18~20 HWY and 16~18 city
.i could not use od so than regeared to 4.88s and get up to 14 mpg highway and 13-14 city, doesn't make sense to me. I only went to 33's why did i take such a large hit in mpg?
is the mpg dominated more by the width of the tire rather than diameter? also i admit i keep my psi lower because the ride was rough. Im hoping new AT's and 15's will do the trick, something in a c rating so that i can keep psi normal.
10-06-2011, 02:43 PM
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Usually a double whamy because you go to bigger heavier tires that also have greater rolling resistence. Went from stock Rubi's to 325/65R18's Nitto Grapplers and lost 2.5 mpg instantly, then switched to 295/70R18's Trail Grapplers and net lost only around 1.5-2.0 mpg. Taller and narrower (giving same footprint as not as tall but wide) lessens rolling resistence.
10-06-2011, 02:54 PM
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Im dreaming of the day i can get 18mpg, i never got more than 19 when the jeep was completely stock. I bought the jeep 2 days later i drove it to florida and back 18.5 19 mpg back and forth. than i lifted it swapped wheels tires 33x12.5 r17 mtz with alloys's, added winch front/rear bumper, tire swing and rock rails. from that moment i was getting 11-12 mpg.
i could not use od so than regeared to 4.88s and get up to 14 mpg highway and 13-14 city, doesn't make sense to me. I only went to 33's why did i take such a large hit in mpg?
is the mpg dominated more by the width of the tire rather than diameter? also i admit i keep my psi lower because the ride was rough. Im hoping new AT's and 15's will do the trick, something in a c rating so that i can keep psi normal.
i could not use od so than regeared to 4.88s and get up to 14 mpg highway and 13-14 city, doesn't make sense to me. I only went to 33's why did i take such a large hit in mpg?
is the mpg dominated more by the width of the tire rather than diameter? also i admit i keep my psi lower because the ride was rough. Im hoping new AT's and 15's will do the trick, something in a c rating so that i can keep psi normal.
. Try staying under 70 on the freeway, 65 makes my millage good. If I do 70~75 on the freeway the millage suffers poorly. Also do you have a auto or manual.
10-06-2011, 02:57 PM
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10-06-2011, 02:59 PM
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Usually a double whamy because you go to bigger heavier tires that also have greater rolling resistence. Went from stock Rubi's to 325/65R18's Nitto Grapplers and lost 2.5 mpg instantly, then switched to 295/70R18's Trail Grapplers and net lost only around 1.5-2.0 mpg. Taller and narrower (giving same footprint as not as tall but wide) lessens rolling resistence.