tire weight/size dilemma
Thread Starter
JK Junkie
Joined: Nov 2009
Posts: 2,737
Likes: 1
From: Rochester, NY
tire weight/size dilemma
I have been reading through the threads on here about tire weight vs. bigger size.
Still don't know which one would affect MPG/power more.
I currently have 285/70R17 Duratracs, which are about 50lb each.
This is just a question, so I will pick two tires that I have been eyeing... and want to know which one will hurt power and/or MPG more?
315/70R17 Duratracs are 60lb each and are 34.4.
305/65R17 KM2s are 67lb each and are 32.8.
(I know a M/T will get less mpg than an AT)
Still don't know which one would affect MPG/power more.
I currently have 285/70R17 Duratracs, which are about 50lb each.
This is just a question, so I will pick two tires that I have been eyeing... and want to know which one will hurt power and/or MPG more?
315/70R17 Duratracs are 60lb each and are 34.4.
305/65R17 KM2s are 67lb each and are 32.8.
(I know a M/T will get less mpg than an AT)
JK Newbie
Joined: Jan 2012
Posts: 83
Likes: 0
From: Dirty Jersey
It's not just the static weight of each wheel/tire, it's also the rotational mass which affects how much more effort the engine has to perform to accomplish the same level of performance.
Rotational mass hurts acceleration/torque.
More width adds rolling resistance AND air drag AND rotational mass.
More diameter reduces torque AND increases rotational mass.
More weight adds not only weight, but also rotational mass.
I've made the choice between those two tires myself(285/70/17), and while I think the Duratrac is the wiser all-purpose/daily-driver choice, i've decided that i'm more likely to get stuck in mud than stuck on ice, so I chose the KM2's.
With the minimal differences in tire dimensions you are looking at, I think HOW you drive will make a bigger impact than which one you choose,....but if mileage was you only concern then i'd go with the lighter Duratracs.
Rotational mass hurts acceleration/torque.
More width adds rolling resistance AND air drag AND rotational mass.
More diameter reduces torque AND increases rotational mass.
More weight adds not only weight, but also rotational mass.
I've made the choice between those two tires myself(285/70/17), and while I think the Duratrac is the wiser all-purpose/daily-driver choice, i've decided that i'm more likely to get stuck in mud than stuck on ice, so I chose the KM2's.
With the minimal differences in tire dimensions you are looking at, I think HOW you drive will make a bigger impact than which one you choose,....but if mileage was you only concern then i'd go with the lighter Duratracs.
Thread Starter
JK Junkie
Joined: Nov 2009
Posts: 2,737
Likes: 1
From: Rochester, NY
Yeah. I am a DD with little trail use.
I am just using those tires as an example. I love my Duratracs, but just wanted to know if the bigger tire with the lighter weight would be better than a smaller tire with more weight.
In all actuality, I am REALLY looking hard at the Load rated C Grabber AT2 and the 305/65R17 E rated BFG AT. Just wanted to know how the added weight would work on my Jeep as opposed to my 50lb Duratracs.
I would go to 35s but I run 3.21s and use premium gas in my rig, so that's out of the question (tow tune). Maybe on my next Jeep.
I am just using those tires as an example. I love my Duratracs, but just wanted to know if the bigger tire with the lighter weight would be better than a smaller tire with more weight.
In all actuality, I am REALLY looking hard at the Load rated C Grabber AT2 and the 305/65R17 E rated BFG AT. Just wanted to know how the added weight would work on my Jeep as opposed to my 50lb Duratracs.
I would go to 35s but I run 3.21s and use premium gas in my rig, so that's out of the question (tow tune). Maybe on my next Jeep.
Thread Starter
JK Junkie
Joined: Nov 2009
Posts: 2,737
Likes: 1
From: Rochester, NY
I am staying with 33s. I was just using the 35" Duratrac as an example. I plan on getting the bfg at or the general grabber at2. I love the 33" size and just want something wider.