Tire Size

[shepherds56]

Newbie questions...Is there any difference in tire size on a 08-09 F350 King Ranch while towing a fifth wheel..I know they have different wheel sizes available..18"/19" amd 20".

[SmokeyWren]

I haven't seen any specs or order guides yet for the '09s, so can't answer anything about them with any certainty.

But we have the specs and order guides for the '08s. And an educated guess says the tires and wheels available for '09 models will be the same as the ones for the '08s.

When you say "F-350", realize there are two completely different pickups that meet that definition, not counting the chassis cabs that also come in two different models.

The one with single rear wheels (SRW) is quite different than the one that has dual rear wheels (DRW).

Most outsiders who aren't Ford freaks think "one ton dually" when they hear F-350. So we'll tackle the DRW first.

Standard is 17"x7.5" J wheels. There are no optional sizes, but you can order aluminum wheels on some models, and aluminum wheels are part of some trim levels, including the King Ranch.

Standard tire size is LT245/75R17E. There are no size options on the dually, although there are tread and sidewall options.

Now to the F-350 SRW, which has more options.

Depending on trim level and other options, your SRW might have one of three different size wheels:

17"x7.5" J
18"x8.0" J
20"x8.0" J

The 18" aluminum wheels are part of the King Ranch SRW pkg. You cannot order 17" wheels on a King Ranch SRW, but you can order 20" wheels on a King Ranch SRW.

There are no 19" wheels available for F-350. (The F-450 has 19.5" wheels, but that's a different topic.)

F-350 SRW tires for those wheels come in several sizes, and each size has tread and sidewall options:

LT265/70R17E
LT275/65R18E
LT275/70R18E
LT275/65R20E

If you'll be towing more than a rowboat, then you probably do NOT want the optional 20" wheels and tires. The tires effectively change your rear axle ratio by 3.8 percent. So if you order a 3.73 ratio with the 20" tires, you'll have the equivalent of a 3.59 ratio .

And speaking of rear axle ratio: Standard on the F-350 SRW King Ranch with diesel engine is 3.55, which is fine for a commuter car. But if you plan to use the truck for towing, then you want the optional 3.73.

For a DRW, standard on a King Ranch with a diesel engine will be 3.73 open axle, and optional will be limited slip with 3.73, 4.10 or 4.30 ratios. Select the rear axle ratio based on your expected max gross combined weight (GCW). If I were ordering it, I'd select 3.73 for loads up to about 20k GCW, 4.10 for loads up to about 23k GCW, and the TowBoss pkg with 4.30 rear end for loads over 23k and up to the max of 26k GCW.

[shepherds56]

Thanks for the info..talking about a SRW F-350 King Ranch..so I gather you would suggest the 3.73 rear end (thats what I want), tow package and an 18" wheel? 5er will be about 11,900 dry so I know it will be heavier (not a whole lot as we tow dry). Thanks for the input

[SmokeyWren]

The 18" tires and special aluminum wheels are part of the King Ranch pkg, and the towing pkg is standard on all Super Duty pickups. But you have to order the optional 3.73 limited slip rear axle.

If you haven't already done it, download the 2008 F-350 Order Guide from Sunrise Ford Fleet, 16005 Valley Blvd, Fontana, Ca, 92335 . Become familiar with what options you might want that are not included as part Lariat trim and King Ranch pkg. Then as soon as Bobby posts the 2009 Order Guide you can download that and already be familiar with the layout. You should be able to see what changed for the 2009 models and spec out your 2009 model.

For example, air conditioning is an option in the order guide, but you don't order it because it's part of the Lariat trim pkg, and the Lariat trim pkg is required to order the King Ranch pkg.