I did it. “Downgraded” F150 to 18 wheels.

[RooflessVW]

Originally Posted by Fawteen
Originally Posted by rooflessVW
Originally Posted by Fawteen
Does a tire size change require the speedometer to be re-calibrated? Aren't mileage calculations based on the OEM tire size, with a smaller size traveling less distance per rotation?

He put OEM wheels and tires on.

According to OP the OEM were factory 20s.

"instead of the factory 20s I didn't want."

I just have sincere doubts that putting smaller than original tires on a pickup will give that much of a fuel mileage increase.

Yeah. His truck came with 20's.

Others of his same make and model came with 18's.

He put 18's on, from the same make and model truck, with tires of the same overall diameter. The new wheel and tire package is lighter and will provide a smoother ride and less unsprung weight.

 

[MNgopher]

As others have pointed out, the change in wheel size and the fact they are OEM wheels does not matter. The overall rolling diameter is the important number for the correct reading of speed and mileage. And has been pointed out, the overall rolling diameter is near identical.

I did the same math when I bought my truck. Realized the overall diameter of wheels was actually a slight bit smaller on the 20' wheels with the aspect ratio and width of the tires installed versus the 18" combination I ended up with. Counterintuitive, but the math doesn't lie... I purposely bought a truck with 18's and not 20's - I felt it rode better, and tire replacement costs were less with better selection, and they offered better protection off road. Our work XL series F150's get 17" wheels...

I wouldn't count on the fuel mileage holding long term either. Give it time - one segment of driving means little,

 

[double vanos]

My ‘11 F150 had 20s. My ‘18 has 18s and you can tell the difference! Interesting you noticed the lower rolling resistance; that was the first thing I was aware of. Then the better ride, then the better mpgs. I test drove basically the same truck with 20s and drove home with one with 18s it made such a difference.

 

[Rob_Roy]

I'm not sure about any fuel economy difference due to the wheel size - seems like the tires themselves would be more likely to impact fuel economy,

We have two 2016 Ford Expeditions in the fleet - one with 18" wheels, the other with 22". Despite the 22" being coupled with the CCD suspension, I think cracks in the road and other sharp bumps are harsher with the 22". There is also a considerably different in the availability of tires for each size; 18" being more common.

 

[meep]

I'll report back with additional mpg numbers. The weekend was entirely in-town driving and it continued to drop, which is more believable. I'll need at least a week to get some clue of an average, and probably longer than that for a few heat cycles to settle the rubber. The lowest it reached as the average continues to accumulate was 20.0, though it's starting to increase now that I'm getting back into the work commute.

 

[Excel]

you also got rid of the Hankook tires,they are horrid even on the 18" F150s which is what came on my ride

 

[buck91]

I've been tempted many times to plus size my 2011's 17 inch wheels but when it comes down to it I just can't find a reason. The 17 wheels will mount rather large rubber without an issue, the handling is superb with LT load E tires and Bilstein shocks, plus why do I want LESS sidewall on a truck which I enjoy taking off the beaten path occasionally? With my 33's, I can always air down substantially if I actually find myself loosing traction (which has not happened in the terrain I've found here in Michigan).

 

[spj]

Well funny you should post this. I have a 15 Explorer with 20 inch wheels and live in a rural area with bumpy roads. Not a fan of the 20's. I do run 18's on winter wheels with snow tires and the extra cushion is noticeable. My stock Hankooks lasted 20,000. I replaced them with Toyo Open County HT's that lasted 15,000 miles. Pathetic. Meanwhile my Continental Winter Contacts that have at least 20,000 on them are only half worn. I just replaced the Toyo's with P265/50R20 Continental Terrain Contact AT and are loving them. No hit on mileage and they are nice and quiet.

 

[meep]

UPDATE. IF there is a mpg difference from the lighter assemblies, for my normal mixed driving it's within numerical noise. While the vehicle feels like it's rolling easier and longer, it may just be that it's a smoother and calmer ride. I could surmise a .3mpg improvement, but the current average is within the normal range for my driving and can't necessarily be attributed to one factor.

I've got a highway trip this weekend, and will update if there's anything notable. My excitement early on for the mpg change was misleading - apologies.

Since mpg was not a factor in the wheel downgrade, I'm still very pleased with the results - it is just what I wanted.

 

[d00df00d]

Originally Posted by Cujet
There is a reason the BMW i3 uses tall, bicycle skinny tires. Lower rolling resistance.

That's the reason for the tire size, yes -- though the contact patch is still supposed to have the same total area as a Mini Cooper's.

I don't think it's clear whether that's the main reason for the wheel size they used, is it? I'd bet good money that looks were a major part of that equation, if not the main factor.

Also, those tires are bespoke. They're a total package: size, yes, but also weight, compound, and construction.

All of this is to say I don't think the i3 is a good guide to what people can expect from playing around with tire and wheel combos on their own cars.

 

[d00df00d]

Originally Posted by meep
UPDATE. IF there is a mpg difference from the lighter assemblies, for my normal mixed driving it's within numerical noise. While the vehicle feels like it's rolling easier and longer, it may just be that it's a smoother and calmer ride. I could surmise a .3mpg improvement, but the current average is within the normal range for my driving and can't necessarily be attributed to one factor.

I've got a highway trip this weekend, and will update if there's anything notable. My excitement early on for the mpg change was misleading - apologies.

Since mpg was not a factor in the wheel downgrade, I'm still very pleased with the results - it is just what I wanted.

Glad to hear you're still liking the results.

The trend toward huge wheels is so stupid. It's great to see someone regaining a measure of sanity.

 

[BMWTurboDzl]

Originally Posted by Fawteen
Originally Posted by rooflessVW
Originally Posted by Fawteen
Does a tire size change require the speedometer to be re-calibrated? Aren't mileage calculations based on the OEM tire size, with a smaller size traveling less distance per rotation?

He put OEM wheels and tires on.

According to OP the OEM were factory 20s.

"instead of the factory 20s I didn't want."

I just have sincere doubts that putting smaller than original tires on a pickup will give that much of a fuel mileage increase.


If the wheel/tire combo weighs less than the factory set up it is possible and then there are differences in rolling resistance between the tires themselves

 

[BMWTurboDzl]

Originally Posted by d00df00d
Originally Posted by meep
UPDATE. IF there is a mpg difference from the lighter assemblies, for my normal mixed driving it's within numerical noise. While the vehicle feels like it's rolling easier and longer, it may just be that it's a smoother and calmer ride. I could surmise a .3mpg improvement, but the current average is within the normal range for my driving and can't necessarily be attributed to one factor.

I've got a highway trip this weekend, and will update if there's anything notable. My excitement early on for the mpg change was misleading - apologies.

Since mpg was not a factor in the wheel downgrade, I'm still very pleased with the results - it is just what I wanted.

Glad to hear you're still liking the results.

The trend toward huge wheels is so stupid. It's great to see someone regaining a measure of sanity.



Increased crumble zones equate to larger cars which require larger wheels to fill the wheel arches .

 

[meep]

Originally Posted by BMWTurboDzl


If the wheel/tire combo weighs less than the factory set up it is possible and then there are differences in rolling resistance between the tires themselves


Agree, it's hard to know since two factors changed, wheel size and tire make/model. Just finished 700 miles over the weekend. Highway mileage is unchanged, which is to be expected. It was significantly quieter and a notabley calmer highway drive, with a slight drop in the "sports car" feel provided with the 20s.

I need to weigh one of the 20s. They are notably heavier (I'm guessing 6-8 lbs?) than the 18s. the shipping weight for the 18s was 27 lbs per carton. I'd read somewhere the naked weight was 23lbs each.