Downsizing Wheels from 20" to 17" or 18": Your Thoughts?

[2014 Laramie CC SB 4x4 w/ 8spd & 3.21s]

Did a search but haven't found any sage advice on this just yet. My thoughts below - feel free to add your $0.02 and if I've missed anything?

No speedometer differences as I believe the dealer can correct for the appropriate sizes (please correct me if I'm mistaken); I also selected the lightest wheels I could aesthetically stand for the purposes of this analysis.

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20" (P275/60/20 Michelin LTX M/S2)
Revs / Mile: 611.6
Engine RPM @ 70mph: 1,535 (70 miles / hr x 1 hr / 60 min x 611.6 revs / mile x 3.21 axle ratio x 0.67 8th gear ratio)
Wheel Weight: ~32 lbs (searching forums)
Wheel Cost: $0 (included w/ truck)
Tire Weight: 41 lbs (Tire Rack)
Tire Cost: $223 ea (Tire Rack)
Tire Diameter: 33" (calculated)

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18" (P265/70/18 Michelin LTX M/S2)
Revs / Mile: 618.8
Engine RPM @ 70mph: 1,553 (same calculation except 618.8 revs / mile)
Wheel Weight: 25.25 lbs (Mamba M14 18x9)
Wheel Cost: $175 ea (Tire Rack)
Tire Weight: 41 lbs (Tire Rack)
Tire Cost: $199 ea (Tire Rack)
Tire Diameter: 32.6" (calculated)

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17" (P265/70/17 Michelin LTX M/S2)
Revs / Mile: 638.4
Engine RPM @ 70mph: 1,602 (same calculation except 638.4 revs / mile)
Wheel Weight: 22.8 lbs (American Racing AR899)
Wheel Cost: $139 ea (Tire Rack)
Tire Weight: 42 lbs (Tire Rack - surprising increase here but there's more tire)
Tire Cost: $197 ea (Tire Rack)
Tire Diameter: 31.6" (calculated)

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Net 20" => 18"
Wheel & Tire Weight: (6.75 lbs) per corner
Replacement Tire Cost: ($24) per corner
One Time Cost: $175 per corner + installation, TPMS, etc.
Truck Ride Height: (0.2") ([32.6" - 33"]/2)
Engine RPM @ 70mph: +18 RPM

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Net 20" => 17"
Wheel & Tire Weight: (8.2 lbs) per corner [22.8 lbs - 32 lbs + 1 lb increased tire mass]
Replacement Tire Cost: ($26) per corner
One Time Cost: $139 per corner + installation, TPMS, etc.
Truck Ride Height: (0.7") ([31.6" - 33"]/2)
Engine RPM @ 70mph: +67 RPM

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I think 17" are the right choice also because of the wider variety of tires available at lower cost and increased impact protection for the wheel.

The decreased unsprung mass, lowered ride height, and increased cruising RPMs should *theoretically* make a fuel economy difference but they're all so small that I expect they'll just get washed out in the noise.

Anyone have any additional thoughts or guidance?

dont go with 18in rims because tires are 50+% more. very spendy so i would get 17's if i were you simply because it will be much less costly in the long run. in your chart is says they are not much more but on my 07 silverado the cheapest tires i could even find ran me $235 a piece

Do you tow anything? Might want to check the tire size and sidewall don't change any tow limits.

I would think the change would make for an even smoother ride...more air & rubber to ride on?

I love the Michelin LTX M&S2's. Had them on my other 2 rigs.

Good thinking RE the towing; no towing/hauling YET but there will be soon. I'll have to check the load ratings on the wheels/tires.

Thanks for the feedback on the wheel size, rammanriley.

I'm definitely leaning towards the 17" combo right now.

I sold my stock 20"s and went with 18's with LT275/70R18E1 Goodyear DuraTracs.
I wouldn't go any other way. I like the look and performance. Didn't have to change the speedo either.

I don't tow, but snow and ice is a major concern and didn't want to run two different sets of wheels and tires in the winter.

Do it, I can't stand 20's. I like the old school 4x4 look and function. Your gears are 3.21, so you weren't concerned about towing when you bought the truck yeah? If you are towing an average trailer or an average boat, you have nothing to worry about. If you are towing a 10k plus pound 5th, you would want a new truck anyhow.

No matter how you slice it 1500's tow between 7k and 10k pounds give or take, and 2500 plus between 16k and 30k pounds. You shouldn't have lower ride height either, you just want to eat up 3 inches with sidewall. Anyhow, unless it is a 2500 don't worry about towing because you can't (or shouldn't) tow serious weight anyway.

BTW, across the board your 3.21 gears call for a minimum 2k pounds decrease in towing weight, and in many instances even 4k pounds!!! Look on the towing guide and enter your gear choice where it says axle ratio. So adding a higher sidewall isn't going to make it worse, you already screwed yourself by opting for the 3.21. I'm sure whatever tire you get you will be able to tow to the limits of your gear, but don't take my word for it double check. Good luck

Looks like you have a 8k pound limit in towing with that gear.

If you get a tire with a smaller diameter, it wont look as nice on a 4x4. At least get a 33, just an opinion on that.

You in love with michelin? That's what I put on my wife's rav 4, but I'd get something like a Toyo or Cooper for my 4x4 rig, just sayin.

My only 2 cents is 265 70 17 just looks small on these trucks.

Like I said, 33 is the minimum on these 4x4 Rams. I need a conversion chart because I don't do metric. Or get a prius and really get some good mileage.

Yeah, the 3.21s were not my choice; this odd combo (color, options, etc.) were the last 2014 on the dealer's lot and they made me an offer I couldn't refuse.

285/70/17 would get to 32.7" but the tires in that category are all pretty hard core off road and *much* about 25% more money. BFG KO2, etc.

I've checked out the towing guide and am fine w/ an 8k towing limit; I actually am fine w/ 7k limit (4 passengers in cab).

There most certainly is a ride height difference (0.7") between the stock 20" size and the alternate stock 17" size. I doubt we will notice it though.

No special love for Michelin - they seem to have the best reviews, despite their increased cost. We don't do any serious off road driving. *Maybe* to the beach in Mexico once a quarter and some dirt roads around the AZ area once a month.

RE Load & Speed Ratings (Michelin LTX M/S2)

P275/60/20 114 T => 2601 lbs max load per tire, 118 mph max

P265/70/18 114 T => same

P265/70/17 113 T => 2535 lbs, 118 mph max

No changes in max speed

20" => 18" no change in max load

20" => 17" (66 lbs) per tire max load

Seems inconsequential given 2535 lbs per tire still works out to be 10,140 lbs for the truck. 10K lbs for the truck is *way* above the max loading specified by the towing guide (5,555 lbs truck, 600 lbs max passengers, 800 lbs max bed load = 6,995 lbs).

I usually go with A/T and for some reason I have never heard once anything good about Michelin A/T's on a truck. Like I said I do like Michelin's on our other vehicle, but for A/T there are a ton of tires that stick out, BF Goodrich, Cooper, Toyo, Goodyear, General, etc etc etc. In personally have never heard anyone put Michelins on a 4x4, but I'm sure as soon as I say someone will school me.

Agreed - you see a lot more A/T tires on trucks, especially in the colder climates.

AZ has pretty mild (nice?) winter weather so we get some more highway-style tires on trucks out here.

I though about doing 18's with 35's when I did my lift but their wasn't any real price difference. So I just stuck with the 20's since I wasn't saving any real money.

Running 35"x12.5"x18" Trail Grapplers here. I think the 18" is a nice medium between the 20" and 17". Wheels dont look too small but you do have more meat on the tires. Tires are MEAN. Took off some ***** front end when she turned into my right rear tire lol. Although it is in the shop for 2 weeks with a little body damage ;/

doz said:

Running 35"x12.5"x18" Trail Grapplers here. I think the 18" is a nice medium between the 20" and 17". Wheels dont look too small but you do have more meat on the tires.

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Nice truck. I agree about the 18"s.

Here's mine with 18"s and 33" tires. I wanted to keep the stock ride height. I have 3 small kids i need to put in the back.

17s, 18s or 20s? Wheel weight? Don't really matter other than get what looks best to you and your wallet. These aren't race spec vehicles in an Indy 500, so it doesn't really matter that much. Bigger side walls will help more for off road and the closer to factory tires you have will help your MPGs.

That is a good looking rig, Doz.

RamWrayzor, you're absolutely right.

Im on their same boat. 18's on 35x12.5x18. Love the look, keeps the tires looking big but at the same time the rims still look big!

rammanriley20 said:

dont go with 18in rims because tires are 50+% more. very spendy so i would get 17's if i were you simply because it will be much less costly in the long run. in your chart is says they are not much more but on my 07 silverado the cheapest tires i could even find ran me $235 a piece

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Really, 50+% more? Where do you shop at?


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