Wheel size and towing?

[texasdiver]

What are the thoughts on the effect of wheel size on towing, payload capacity, and gas mileage? Take the Ford F250 and F350 for example.

The XL and XLT models come with 17" wheels standard
The Lariat and King Ranch come with 18" wheels standard
The Platinum comes with 20" wheels standard.

After a bit of googling I have discovered that tires for 20" rims are significantly more expensive than for the smaller rims. But I haven't found a clear answer on which size wheels are most ideal for trailering and 5th wheels. Or for that matter, which are most efficient in terms of gas mileage.

If one is buying the truck primarily to haul a 5th wheel, is there any particular reason to prefer one wheel size over the other? Inquiring minds would like to know.

[spud1957]

Tire size does not change any of the ratings for the F250. The tire size does have an effect on the F350. If you select the 17" wheel/tire option on the F350, the RAWR is decreased to 6290. This a result of the 17" max load capacity which is less than the 18/20".

S

[APT]

Keep it simple.

20" wheels look nicer on trucks to most people. 20" wheels cost more than 17" wheels, either new or aftermarket. Tires for 20" wheels generally cost more than tires for 17" wheels. If you plan on keeping the truck through multiple sets of tires, you should understand by how much and take that into budget consideration.

Buy what you think looks nice enough and can afford. Tow ratings and loading do not vary enough to be concerned with IMHO.

[Terryallan]

Check out your TV owner's manual. It will tell you in there. Which size stock tires will tow more, and which will tow less. On my 150. The factory stock tire, size 17" tows 500lbs MORE than the factory stock 18" tires.

[naturist]

The TIRE rolling diameter is the controlling dimension here, along with axle ratio. A smaller rolling diameter has the same effect as a larger axle ratio: that is, the wheels make more turns per mile, increasing the torque at the wheel. A larger rolling diameter and a smaller axle ratio decrease the number of turns per mile, and also decrease the torque.

It is probably possible to buy tires with the same rolling diameter regardless of whether you buy 16 inch wheels or 20 inch ones. The difference will be reflected in the aspect ratio of the tire dimensions, for example, an 85 series tire on a 16 inch wheel could have the same rolling diameter as a 20 series tire on a 20 inch wheel.

But there is one other important factor to consider: the tire's resistance to damage from hitting rocks/curbs/potholes. I believe you'll find that the 20 series tire will be much more easily damaged than the 85 series tire, due to the much shorter sidewalls, which afford less room for the sidewall to collapse into before damage occurs, and the larger air volume of the larger tire will cause less of a rise in pressure due to a given deflection of the tread.

Upshot: I'd stick to 16s and 85s or 75s for rough duty and leave the 20s for your pimpmobile.

[texasdiver]

jmtandem wrote:

What are the thoughts on the effect of wheel size on towing, payload capacity, and gas mileage? Take the Ford F250 and F350 for example.

The XL and XLT models come with 17" wheels standard
The Lariat and King Ranch come with 18" wheels standard
The Platinum comes with 20" wheels standard.

After a bit of googling I have discovered that tires for 20" rims are significantly more expensive than for the smaller rims. But I haven't found a clear answer on which size wheels are most ideal for trailering and 5th wheels. Or for that matter, which are most efficient in terms of gas mileage.

If one is buying the truck primarily to haul a 5th wheel, is there any particular reason to prefer one wheel size over the other? Inquiring minds would like to know.

It also depends on the axle ratios. If the ratio is compensated for the 20 inch wheels and would be essentially the same as the 17 inch wheels with its ratio the towing differences should be moot. There may be slight differences in handling depending on the aspect ratio of the tire in corners but for most travel trailer and fifth wheel folks that differenece is probably not a priority. If the axle ratio and engines/transmissions are the same then the larger the tire the less rpm's per mile, less rpm's at any given traveling speed and less effective power. But, all that is blurred with transmissions and the ability to use gears to compensate. Some like 19 inch tires to With modern diesels it is hard to think that anybody would run out of power so get the wheels/tires you like and enjoy the trip.

I understand that one can replicate more or less the same outside tire diameter by using higher or lower profile tires. My question is more along the lines of which is preferred for payload and towing? Higher profile tires with smaller rims or lower profile tires with larger rims? And is there a preferred rim size that will make it easiest to find replacement tires on the road should I experience a blown tire in some backwater town? I'd hate to be stuck in the middle of nowhere and find out "sorry...we can't help you, you should have gotten the 18" rims"

[jmtandem]

What are the thoughts on the effect of wheel size on towing, payload capacity, and gas mileage? Take the Ford F250 and F350 for example.

The XL and XLT models come with 17" wheels standard
The Lariat and King Ranch come with 18" wheels standard
The Platinum comes with 20" wheels standard.

After a bit of googling I have discovered that tires for 20" rims are significantly more expensive than for the smaller rims. But I haven't found a clear answer on which size wheels are most ideal for trailering and 5th wheels. Or for that matter, which are most efficient in terms of gas mileage.

If one is buying the truck primarily to haul a 5th wheel, is there any particular reason to prefer one wheel size over the other? Inquiring minds would like to know.

It also depends on the axle ratios. If the ratio is compensated for the 20 inch wheels and would be essentially the same as the 17 inch wheels with its ratio the towing differences should be moot. There may be slight differences in handling depending on the aspect ratio of the tire in corners but for most travel trailer and fifth wheel folks that differenece is probably not a priority. If the axle ratio and engines/transmissions are the same then the larger the tire the less rpm's per mile, less rpm's at any given traveling speed and less effective power. But, all that is blurred with transmissions and the ability to use gears to compensate. Some like 19 inch tires to With modern diesels it is hard to think that anybody would run out of power so get the wheels/tires you like and enjoy the trip.