I almost piggy backed on the leveling tire size thread from a couple of months ago because there was a lot of great information shared, but decided it was different enough to warrant its own thread.

Does anyone have an idea about what the largest tire size you can fit on a stock 2023 4x4 crew? I've surfed all through the F150 message boards, and I can't find any sort of definitive answer because almost everything is focused on leveling kits and answers are entirely inconsistent.

Stock tire size is 275/65R18 which everything online shows as 32.1" diameter, but I get barely over 31 with a tape measure, which makes this even more confusing for me because I don't trust the nominal sizing guides.

Maybe a 275/70/18. I would just go to a discount tire or whatever store you buy tires from, and ask them to put one on and test if it rubs.

Are you measuring with the tire off or on the truck?

Anyhow 275/70/18 will get you just over 33" and shouldn't have any rubbing. My brother had that in his f150

Not many SL options in that size though. Most are E rated

ttha_aggie_09 said:

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Maybe a 275/70/18. I would just go to a discount tire or whatever store you buy tires from, and ask them to put one on and test if it rubs.

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This, I went up to 275/70/18s on KO2s and it's as big as you'd want to go on the front.

I have the same truck as OP.

Correct. I had to (wanted to though for an AT tire and more stability with towing) go to an E rating.

It has hurt gas mileage, more than I would have thought but I still average about 17.5mpg on the 3.5L boost.

Yeah the Es weigh about 12-15lbs more a tire than the SL and maybe 10lbs heavier than a D. I'm going through this dilemma right now and prefer not to go E if I have a choice but that's tough on 20" wheel in the size I am looking.

Any of you guys that have made the switch to the 275/70 track your mileage really closely? I have the 5.0 with 3.31 axle and I've averaged 18.3mpg over 45000 miles. Curious what you guys have calculated as change after making the switch.

That measurement is mounted. I guess I could tape the spare, but I didn't think it would make a full inch of difference.

CivilEng08 said:

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Any of you guys that have made the switch to the 275/70 track your mileage really closely? I have the 5.0 with 3.31 axle and I've averaged 18.3mpg over 45000 miles. Curious what you guys have calculated as change after making the switch.

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I'm getting 17.5 or so. Mostly highway driving but there's some stop and go. I also go about 75 which sucks gas on the 3.5 with the turbos spooling.

I think I lost close to 1pmg with the tires.

For reference, 3.5L EB with 3.55 gears (Max Tow package). 275/70/18 BFG KO2s

I'm running Toyo AT3 33x12.5/20 on a 2" level with no issues.

Eye balling it looks like it would be fine without the level.

I put on 35 12.5 17 on 2012 150 with bilstein level. I had to cut about an inch of the front wind dam for reversing. I can tell you it looks great but it's like pulling a loaded trailer now. Constantly shifting into 5th then 4th gear at road speeds. Taking off is like in slow motion. Would not recommend to anyone.

That's prob a jump from 35 to 60+ pounds per tire. That's a lot of rotating weight

He's also learning about gear ratios

I recall my first full size truck purchase

F150 with a 3.15

Never again

Same boat as well. Consensus is 275/70/18, but again mostly E range options. I'm considering 285/65/18, as a few SL options without the weight and stiff sidewall. I've changed my mind 50 times but still yet to pull the trigger.

I'm looking 285/65 or 265/70

More options with the 265 and you lose .4" in overall width