Overlanding Tire and Wheel size

[Whiteout]

HI all! This is my first thread. So I hope I put in the right section. I'm looking to put some new rubber on 2016 F150. The truck came with 275/65R18 (32.1 x 10.8 with a 7" sidewall). I was thinking about going with a 20" wheel (really like the Fuel Contras) and 296/60R20 tire (34 x 11.6 with 7" sidewall).

Every time I say I'm going to a 20" wheel, people always say I don't have enough sidewall. to air down. What is enough sidewall air down? Thoughts?

 

[MazeVX]

I have no idea what size tire you can run, but I can say something about the 20"

There's a company here who started running 275/65r20 wich is 34" they did a lot of testing before they started selling them to their customers but they are happy with it, they balance better and run better on the street and they say they don't see any problems off road.
Personally I think it's the truth, possibly in situations where you want to air down extremely you should be very careful.

 

[chrishesselden]

HI all! This is my first thread. So I hope I put in the right section. I'm looking to put some new rubber on 2016 F150. The truck came with 275/65R18 (32.1 x 10.8 with a 7" sidewall). I was thinking about going with a 20" wheel (really like the Fuel Contras) and 296/60R20 tire (34 x 11.6 with 7" sidewall).

Every time I say I'm going to a 20" wheel, people always say I don't have enough sidewall. to air down. What is enough sidewall air down? Thoughts?

A heads up, I have same truck with factory rims and I’m having a hell of a time finding anyone locally that sells off-road worthy tires. Maybe it’s just the brand I’m looking for that no one sells but thought I would pass along the troubles of having a 20” rim.

 

[Whiteout]

A heads up, I have same truck with factory rims and I’m having a hell of a time finding anyone locally that sells off-road worthy tires. Maybe it’s just the brand I’m looking for that no one sells but thought I would pass along the troubles of having a 20” rim.

Thanks. Any tire change for me will mean new wheels. And I'll be ordering ro save the sales tax.

 

[Whiteout]

I have no idea what size tire you can run, but I can say something about the 20"

There's a company here who started running 275/65r20 wich is 34" they did a lot of testing before they started selling them to their customers but they are happy with it, they balance better and run better on the street and they say they don't see any problems off road.
Personally I think it's the truth, possibly in situations where you want to air down extremely you should be very careful.

Airing down is abt the size and strength. Just not what's too small. I had a 15" wheel on my XJ so a 33" had plenty of sidewall. Never aired, since most of its life was on the street. Hopefully, I'll change that with my F150

 

[smritte]

First off, I love my Fuel rims. Unless it changed in the last year, 17's have the most variations on offroad tires. I think your question would be better answered by, where do you drive off road and how much. Your tire absorbs small bumps, the shorter the sidewall the less it does it. For me and my driving, 17" on 315's is perfect. 305's will still work, 295's are pushing it. My 315's on a 20" wouldn't be too bad but, any smaller tire, I think I would rock rash the rim some and ride poorly. This would be from not noticing a pothole or rock on the road. My best tire pressure on dirt roads is 15 psi. A little more sidewall flex for the rough road and stable enough to drive pavement for a bit if needed. This is how I based my opinion.

Other question's would be, do you tow and how much do you put in the back? If you have a bit of weight (heavy trailer, hauling heavy items), your tires need a better load rating and that will start to limit your choices.

The 20's would look cool though.

Scott

Edit: My tire sizes are based on 17" rim's. Obviously same tire size on 20" would be different. Its also not a good idea to go to a smaller rim than stock. The brakes may not clear a smaller rim.

 

[Theoretician]

It’s not a situation where there is hard line between enough sidewall to air down and not enough sidewall to air down. The best idea is simply to have as much rubber as possible so that you can air down as low as possible when necessary. With that in mind, I got 285/75r18 ridge grapplers for my regular cab F150 (no crash bars in front of the tires). They do rub a bit in specific circumstances, but going from 7 inches of sidewall to 8.5 inches resulted in a noticeable increase in ride quality, as well as less sidewall deflection for a given pressure which means less heat generation within the sidewall which means less risk of doing damage to the sidewall at low pressures.

Judging by the look of the sidewall, on the stock 275/65r18 tires I wasn’t comfortable going below roughly 22 psi for general use. With the new tires, I’m comfortable going down to about 18 psi in the same conditions.

 

[Whiteout]

First off, I love my Fuel rims. Unless it changed in the last year, 17's have the most variations on offroad tires. I think your question would be better answered by, where do you drive off road and how much. Your tire absorbs small bumps, the shorter the sidewall the less it does it. For me and my driving, 17" on 315's is perfect. 305's will still work, 295's are pushing it. My 315's on a 20" wouldn't be too bad but, any smaller tire, I think I would rock rash the rim some and ride poorly. This would be from not noticing a pothole or rock on the road. My best tire pressure on dirt roads is 15 psi. A little more sidewall flex for the rough road and stable enough to drive pavement for a bit if needed. This is how I based my opinion.

Other question's would be, do you tow and how much do you put in the back? If you have a bit of weight (heavy trailer, hauling heavy items), your tires need a better load rating and that will start to limit your choices.

The 20's would look cool though.

Scott

Edit: My tire sizes are based on 17" rim's. Obviously same tire size on 20" would be different. Its also not a good idea to go to a smaller rim than stock. The brakes may not clear a smaller rim.

Thanks, Scott. Great point about the 17s. I should be good with either the 17 or 18 rim. Make sense that Ford put 17s on the Raptor. DK

 

[Renegade]

I have 20 inch wheels on my 2500HD for years now. There are plenty of OffRoad tire choices, KO,KM,STT, MT/R, on and on. I usually run a 285/65/20.

While I am not a big fan of airing down,I have never had an air-down issue, granted I do not run a 6psi, but I can certainly drop them down some when I am beachs/sand.

 

[CaseyW]

HI all! This is my first thread. So I hope I put in the right section. I'm looking to put some new rubber on 2016 F150. The truck came with 275/65R18 (32.1 x 10.8 with a 7" sidewall). I was thinking about going with a 20" wheel (really like the Fuel Contras) and 296/60R20 tire (34 x 11.6 with 7" sidewall).

Every time I say I'm going to a 20" wheel, people always say I don't have enough sidewall. to air down. What is enough sidewall air down? Thoughts?

One "rule of thumb" I've seen from very experienced overlanders is going leaning to "tall and skinny" vs. a wider tire as they are more versatile. Another is to have the sidewall equal to the width of the tire.

 

[Renegade]

. Another is to have the sidewall equal to the width of the tire.

Are you sure you got that right? That would be a 1:1 aspect ratio, I am not sure anyone makes that in standard size SUV tires. Most are 55-70 range.

 

[MazeVX]

Are you sure you got that right? That would be a 1:1 aspect ratio, I am not sure anyone makes that in standard size SUV tires. Most are 55-70 range.

He's right with that but that's more like a theoretical option, you probably find it with 15" rims, something like 31x9,5r15 goes that direction.
A good balance are the 285 or 275 metric sized tires like 285/75r17.
You also can change the way a tire get deformed by the width of the rim, for example the 285 on a 9" rim will get wider with lowered air than on a 7,5" rim.
ASPW talked about this topic in some of his videos.

 

[Renegade]

He's right with that but

Who makes a tire in that size with 100% aspect ratio?

you probably find it with 15" rims, something like 31x9,5r15 goes that direction.

31x9.5r15 is 84%

A good balance are the 285 or 275 metric sized tires like 285/75r17.

Those are 75%.

 

[smritte]

going leaning to "tall and skinny" vs. a wider tire

Taller does work well all around. Nice footprint and less resistance on highway. Wider only stands out if you need to float on top. Too bad there are very few tall skinny tires out there. I have 33 10.5 BFG's on my trailer. They stopped making the 33 9.5's. I would love to get a 35 9.5 for my cruiser that wasn't a super swamper or some other aggressive mud tire.

As everyone has said, 285 75 R17 (example). The 75 is the aspect ratio. 75% of the tread (285mm). Math comes out to 213.75 mm sidewall. Ive seen commonly 75-85 aspect ratio's. Never seen a 90-100 (in an LT). would be nice.

Scott

 

[MazeVX]

Who makes a tire in that size with 100% aspect ratio?


31x9.5r15 is 84%



Those are 75%.

As I said it is a theoretical thing...
The 31" goes that direction ...
And the 285 just work great ;-)

The highest aspect ratio with metric tires I actually know is 85%

 

[chithead]

Interesting info. Trying to decide on tires for our Wrangler and Grand Cherokee. I was very convinced to go with 35" tires on the Wrangler since we do mainly trails with lots of berms in them, and the Unlimited seems to rub right in the middle of the frame when going over some of them on the stock setup. Figured a 2.5" lift and 35's would fix it. But seeing more and more members her just running 35" tires and seem to do just fine.

Wish that Grand Cherokee would fit 33" tires without tearing the front bumper off