Looking at the owners manual, a 2008 F-150 Crew Cab 4x4 (139" wheelbase) with 20" wheels (275/55/20), and 3.73 gears, has a towing capacity of 8800 lb. The AWD Limited I own has a towing capacity of 5100 lb. The tires (275/55/20 and 275/45/22) are almost exactly the same diameter so I am assuming that it is the lower profile 22" tire that is causing the lower tow rating. Could I put a set of the 275/55/20 on my Limited and expect the same towing capacity of the Regualr 4x4? apprx 8800 lb?

Also, is there anything else about the Limited that casues this decreased towing capacity? Maybe the softer, sports suspension? Any help would be greatly appreciated.

 

The lowering of your tow capacity has nothing to do with tires and wheels. It is the fact that it is AWD. A totally different drivetrain setup than a regular PU.

 

Why would sports suspension be softer?

Anyway, I think we've been here before. Are you sure you have AWD? I thought the only AWD F-150 was the HD. If it is the standard 4wd system, going to a more load-rated tire will get you back to 8k+ tow ratings. If it really is AWD, then you are stuck with the lower rating. I still wouldn't want to tow more than about 7500 pounds with any 1/2 ton.

 

yea, it is the AWD system...the same as the HD...the tires on there now are the 275/45/22 with an XL load rating...I was hoping it was the lower profile tire...oh well...doubt that I will ever tow that much, but it does kind of limit the size of boat I was looking into purchasing! Thanks for the replies.

 

I think you will find the HD has the same limitations. Due to the AWD. Also the Pirelli 20" that you mentioned in your first post on the screw are XL P series tires, so that is not the difference.

 

I am not sure it is the AWD system that is limiting the towing capacity...if you look at the 4x2 limited it has a towing capacity of 5300lb...so that would eliminate the AWD being the culprit in the low tow rating. This is driving me nuts!

 

The Limited is basically a luxury car that looks like a truck. It's the whole package - both tires and suspension - that limits it.

 

It's those heavy chrome letters on the bed. I wanted a Limited soooo bad - and found a dozen of them locally. I need to tow, so I looked into it like you. I never found out why the load capacity was so low, but I also got digusted before I could find out. I still think it's the tires and rims. Even though the tires are P-metrics with Extra Load Capacity, has anyone actually looked at their load? It may be extra load, but an average 22" may only have a 1,500# rating where an extra load 22" has 1,800#. I'm betting it is the 22" rim over anything. I haven't heard of a heavy load 22" rim with such a small bolt pattern.

 

The 20" Pirellis and the stock tires that come on the F150 are P series also. With the Pirellis being extra load, so I just can't say it is the tires and rims. My truck cam with Hankooks, P-series, std load, and the tow rating is well above the Limiteds.

 

Actually, going with a smaller sidewall will drop the load capacity. The tires use the air to support the load and disperse the heat, so less air you can put into a tire (by volume, not pressure) the less your tire is able to support.

Now, would the difference he is talking about make a difference in his application, maybe, maybe not.

 

I still believe it is not the tires. Looking at the specs of the 275/45R22 compared to the 275/55R20, it has a higher load capacity than the 20". Not by much, but still higher. 2496 for the 22" and 2403 for the 20". You do have to take off about 10% of that capacity since it is being used on a truck, but it is still over the axle capacity. Note, both these tires have a 200lb advantage compared to the Hankooks that come std.