The OEM 275/65/18 Continental tires on my F250 are well worn at 33k miles. I have been debating up going with a taller and/or wider tire to fill the wheel wells a bit more. Much of the info I find on the truck forums involve guys trying to stuff 37" tires on a factor truck but I don't want to go that extreme. I understand a taller tire will throw off the speedometer a bit but will a 275/70/18 (or similar 34-35") tire effect towing my 7000 lb trailer? I have the 3.73 gears.

Go up in a gear, go down in towing ability. You need to look at wheel width when going up in tire size. Often times a bigger tire is going to need a wider wheel.

Iraqvet05 wrote:The OEM 275/65/18 Continental tires on my F250 are well worn at 33k miles. I have been debating up going with a taller and/or wider tire to fill the wheel wells a bit more. Much of the info I find on the truck forums involve guys trying to stuff 37" tires on a factor truck but I don't want to go that extreme. I understand a taller tire will throw off the speedometer a bit but will a 275/70/18 (or similar 34-35") tire effect towing my 7000 lb trailer? I have the 3.73 gears.Yep. You are in effect changing your rear gear to a higher gear. So that will hurt your towing ability. Your truck will have to work harder to do the same thing. You are giving up MPG, and power, and torque.

The sizes you list are only going from a 32” to a 33”. The upsize tire will have a slight effect but I doubt you'll even notice. You'll have no problem with your 7k tt. Even with 35s you’ll be fine. You’re not even towing half of what your stock truck is rated for. When you go 37's+ you want to consider regearing as the change is significant.I have 35's on my truck and the only difference is a slight drop in mpg. Less than 1mpg difference which I blame more on the aggressive AT tread. I did have the speedo corrected and lifted the front (2" level) so they don't rub. Biggest issue is visual. Looks great without the tt but it sits slightly ass low with the tt hooked up since it doesn't have the factory rake anymore. Could add a spacer in the rear or add bags but it doesn't bother me for the few times a year I tow.

You are talking maybe a half inch over all Siam difference. Your 3.73 might now be a 3.6-3.65.....3.55 at tallest. A 2" inch taller tire would put you at a 3.42 effective ratio.Your rim will not matter, as both tire sizes are 275mms wide. Only difference is that sidewall height. Marty

Larger tires will change the effective gearing by an amount proportional to percentage of the diameter. That may be a small amount. However, larger tires weigh more. Your OEM tires might weigh 50 pounds each while the proposed 34" tire weighs 65 mounds. You will likely feel that in terms of more fuel used, increased brake wear, and slower acceleration.I experienced exactly this with my prior tow vehicle. It sure looked sweet, but going back down to stock size really woke the truck up.

Tire upsize? | Good Sam Community

macjom
Explorer
Jan 24, 2019
My F250 has 20-inch rockstar wheels with 295/60 tires. Have an aftermarket rear stabilizer bar. The ride quality is good and no wobbling.
ksss
Explorer
Dec 21, 2018
I went from 265/7018 OEM to 285/70/18 on a 2018 3500 Duramax. I am going back down to 275. The truck looks great but it I lost a couple mpg in the process. When I pull real heavy it is even worse.
Super_Dave
Explorer
Dec 21, 2018
My 06 Dodge came with 16" wheels and the gap between the rear tires and the wheel wells is gigantic. I'd love to fill that space with rubber but don't want to hurt my performance.
Hannibal
Explorer
Dec 20, 2018
I also went to 265s from 245s on our F250 to correct a fast reading speedometer. It corrected the speedo, looks better and I can't tell any difference in towing power.
Sandia_Man
Explorer II
Dec 20, 2018
We went from stock 245s to 265s, they are just over an inch taller and less than an inch wider, did not see much of a difference in towing prowess with our 4.10 gearing.

All we noticed at first was they were a bit squirrely being that the new tires had a more aggressive tread design, and were constructed with stiffer sidewalls and harder rubber compounds for their extended mileage rating.

About a mile difference on the speedometer in town and 2mph at highway speeds. Since we tend to do most of our RVing off the beaten track we really appreciate these tires as opposed to the stock LT highway tires.
ScottG
Nomad
Dec 20, 2018
Deleted
Iraqvet05
Explorer
Dec 20, 2018
285/70r18s are a 33.7" tire but that size seems to be an odd one. I found a few but they are aggressive treaded ATs in the $300-400 price range.

I may stick with a 275/70r18 for a price break and availability. This size is optional on the 2017 F-250s that I assume come on 4.11 geared trucks. This tire is only 33.2" and only 1" larger than my current tires.
Garry_Gayle
Explorer
Dec 20, 2018
I went with a 255/80R/17 Toyo Open Country AT on my 15F350 DRW and my gears are 3:73 and I'm towing a 13 38" Mobile Suites 19K loaded with no issues, I can barely tell the gear change. Improved my handling over the stock tires.
Grit_dog
Navigator
Dec 20, 2018
ScottG wrote:
I went from a 265 to a 285 both series 75 and it was a terrible mistake - even with extra power. Then I went to a 285/70 and it works well. (our TT was 7300#)
If you tow, don't go much bigger in dia or it will suck.

Ya because you have a better geared trans than the early G56 in ours!
With 3.73s and 34-35" tires, the old Dodge could still use a 7th gear. Anything over 80 mph is really screaming!
Lynnmor
Explorer
Dec 20, 2018
old guy wrote:
I went from 265 to 285's and I pull mine just fine. I have a 35 ft TT and it weights in at 8500 lbs.

But what size are the tires? :h Incomplete information.

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