Tires affecting MPG

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Tjsieberg

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My 1500 with the 5.7 Hemi is about ready for new tires. I bought the truck with 35/13.5R18 tires that are fairly aggressive. With these tires I have only been averaging 15.4 mpg on the highway. I was thinking about buying new 20 x 9 rims for it and getting a more stock size tire such as the 275/60R20 that came on the truck from the factory. I would still like a fairly aggressive tire but nothing crazy. How much will these smaller tires improve my fuel economy? I drive the truck mostly on the highway and don't pull trailers with it very often. Is it even worth the time and money to find new rims or will I just be wasting my time and money? Any recommendations for tires or rims?

Thanks, Trevor
 

LouM

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Why 20's?
18's can easily be the same height.
265/70r18 are 32.6" in diameter
And the taller sidewall will usually result in a better ride and traction

And 18's cost a lot less normally.
 

RamDiver

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Why 20's?
18's can easily be the same height.
265/70r18 are 32.6" in diameter
And the taller sidewall will usually result in a better ride and traction

And 18's cost a lot less normally.

And if using them in snow or offroad, narrower tires with more sidewall are a big advantage.
I think my winter tires are 255/75-17 or close to that.

Update; My BFGs are 245/70R17 and they perform fantastic in the snow & crud. :cool:

I have summer & winter wheels because of the local conditions here. Sometimes it takes 36 hours before they plow in my area, the joy of rural life.

I don't care, it makes owning a truck with BFG KO2's that much more fun. :cool:
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Burla

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I didnt like the 20's on my 1500 and went with 18's, same sentiment above with the larger side walls and how trucks are supposed to look and function, you don't own a chevy I hear those guys love thin tires with no tread.

If you do opt for your plan, slam it. I have warmed over the years for this on rams, but for me I prefer a lifted truck. your mpg gains would be noticeable, 1-2 mpg. BFG tires white label out are pure truck ****, if that aint your thing consider a drop so the lack of air moving under truck will please you at the pump. Get creative with air damns you will likely gain even more. Get a michelin defender tires or some smooth tire. You are in Minn and those BFG's will hunt in the snow. You have more decisions then just mpg's looks like.
 

CanRebel

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My Rebel come with 18's and I switched to 20's.

As few others above mentioned. Putting 18's will help. If you search in your local area or even some dealers.
You might find some new and/or used 18's that someone switched.
 

ThunderMug95

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Yeah if you look at local forums like Craigslist or Marketplace, you can find take-offs etc. i picked up a set of 20x9 Ram Sport 5 spokes a couple years ago for $300 with bald tires…Just because. Twice in the last month have seen Gen 5 Rebel wheels on Marketplace. Ram switching to 6 lug was a dirty trick…
 

RamDiver

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I found OEM steel 17" 5-bolt take-off rims from my dealer for $69 Canadian, what's that, $29 US? :cool:

I wish my Warlock would fit the 18" 6-bolt rims, then I could have used tires from my previous truck and saved a pile of cash. My local guy found 18" rims for $110 Canadian.

The point is, regardless of the size, ask the stealership, you never know without asking and that much is free.
 

Wild one

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I found OEM steel 17" 5-bolt take-off rims from my dealer for $69 Canadian, what's that, $29 US? :cool:

I wish my Warlock would fit the 18" 6-bolt rims, then I could have used tires from my previous truck and saved a pile of cash. My local guy found 18" rims for $110 Canadian.

The point is, regardless of the size, ask the stealership, you never know without asking and that much is free.
Last set of 20" sport rims i bought from my local dealer as brand new take-offs,got them for $300 Canuck,then turned around and sold the SRA's off them for $400,so made a $100 bucks and got 4 brand new rims for free.That was before Covid,not sure i'd still get them at that price now though.
 

RamDiver

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id love to get rid my 20s for 17s or 18s. my tires are faily new as well.


Maybe, explore Kijiji or Facebook Marketplace. You'd most likely have to buy, set up & install the smaller wheels before listing yours. Don't forget to check the stealerships for take-off rims, if you're OK with OEM steel. Sometimes the prices are excellent and beat jobber prices for the same rim.

BTW, 17" are 5-bolt and 18" are six-bolt, at least for the OEM rims which will be hugely cheaper than aftermarket.

You can always adjust tire sizes, width/ratio to arrive at the required circumference size, that's easy.
:cool:
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nekkidhillbilly

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i have a 4th gen so its a 5 bolt. ive been looking its kinda nill. id like to run aftermarket wheels. id trade mine plus some cash for a good set of aftermarket wheels and tires if someone was close and interested.
 

Dave Haddon

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So for those not clued into this 20 vs 18 rim size on the 2021 Warlock..4 th Gen Classic. What is the skinny on the diff? I hate it when you see trucks with all the wheel well showing. Like to see a truck with a beefy powerful stance. Any info appreciated as I too am looking at summer wheels..thanks guys...
 

Randy Grant

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18' rims with stock size tires will give a softer ride and better MPG than oversize wide tires. Smaller footprint. Inflation also makes a big difference. Diameter, width, tire weight, and tire pressure are the controlling variables.
 

2020PW

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This is an issue everyone overlooks.

You have to replace the summer air with spring, fall and winter. Don’t forget about city air vs country air, north with south, east with west.
 

kurek

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So for those not clued into this 20 vs 18 rim size on the 2021 Warlock..4 th Gen Classic. What is the skinny on the diff? I hate it when you see trucks with all the wheel well showing. Like to see a truck with a beefy powerful stance.

Run whatever outside diameter you want; just about every combination between wheel diameter and tire outer diameter is available. They all have their compromises and strengths. Your stock tire size is 275/60R20 which has a width of 10.8" and a diameter of 33" . An almost identical tire size to fit a 18" wheel would be 275/70R18 - this is the same width but 0.2" larger diameter.

If your truck is not lifted and you do not want to change wheel offset you should have no difficulty fitting a 285/70R18 which is just under 34" outer diameter and will just barely clear the upper ball joint on standard scrub radius. If your new wheels have an appropriate offset you can also run 295/70R18 which is just about 34" & offers a much larger range of choices in tire brand/style but would not clear the upper ball joint without changing wheel offset which affects handling.

I run a tire size that you'd likely disapprove but that's because I put function over form & a larger tire would cost more to buy, cost more fuel to turn, not fit in the stock spare tire location, not fit with stock wheel offset and necessitate a larger scrub radius & as a result track poorly on rutted or crowned highways. Easy choice for me because to my eye what works well is what looks good - there is no conflict.

Incidentally I also have a couple old Mustangs from an era that didn't have traction control nor the benefit of today's snow tire technology and Ford famously left a generous amount of room for tire chains. This should be easy to accept but it really seems to bother a lot of people when a wheel gap exists.
 
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RamDiver

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So for those not clued into this 20 vs 18 rim size on the 2021 Warlock..4 th Gen Classic. What is the skinny on the diff? I hate it when you see trucks with all the wheel well showing. Like to see a truck with a beefy powerful stance. Any info appreciated as I too am looking at summer wheels..thanks guys...

Regardless of the rim size, 17, 18, or 20", the wheel diameter should be relatively the same unless you're OK with a huge error on the speedo or you correct the wheel size with Alfa OBD or a similar app.

If you increase to anything bigger than about a 285/70R17, you will likely require a lift and/or offset adjustment.

The subjective difference in appearance will be lots of sidewall rubber or very little sidewall. Larger rims with low-profile tires look funny to me and this translates into a rougher ride because there's less rubber for a cushioning effect.

BTW, my '21 Warlock has 5-bolt rims which in the OEM rim size is 17". The OEM rims for 18" are 6-bolt.

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