tire ratings

[plugugly]

how much is enuf. i see ratings from 3 to 3800 ina variety of tire options. how much do you really need if towing a 10K trailer, bumper pull?

[SmokeyWren]

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how much is enuf. i see ratings from 3 to 3800 ina variety of tire options. how much do you really need if towing a 10K trailer, bumper pull?

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If we're talking tires for the pickup, your F-250 will work just fine and dandy with tires rated 3,000 pounds each. If you put more than 6,000 pounds on your rear tires, then you're going to be way over the 8,800 GVWR of your tow vehicle.

Worst case is a CrewCab 4x4 PSD longbed. Load it up for a long trip with passengers, tools, cooler, etc., and it could weigh up to 9,000 pounds before you tie onto the trailer. A wet and loaded tag trailer grossing 10,000 pounds should have 1,100 to 1,200 pounds of hitch weight. If your hitch weight is 1,200 pounds, that leaves 4,800 pounds for rear axle weight before you hitched up the trailer. And your rear axle weight probably won't be even close to 4,800 without the trailer.

So what's the chances of having more than 6,000 pounds on the rear axle if the trailer grosses 10k? Slim to none.

And with 9,000 truck weight plus 1,200 hitch weight, that's a GVW of 10,200. Yeah, that's way over the GVWR of the truck, but we're only talking tires now - not the rest of the tow vehicle. With or without the trailer hitched up, you'll not have even close to 6,000 pounds max tire weight limit on the front axle. And based on my weight tickets over several years, you'll not have 6,000 pounds on the rear axle either.

Maybe 5,500 on the rear axle and 4,700 on the front axle when you gross 10,200 - depending on how you adjust your weight-distributing hitch. That gives you several hundred pounds of leeway on both axles in case you have improper load distribution on the trailer.

If you meant trailer tires, a 10,000 pound tag trailer should have not more than 9,000 pounds on the trailer tires. That's 2,250 pounds per trailer tire. I like at least a ten percent fudge factor, so the minimum trailer tire I would prefer would have a weight capacity of at least 2,475. So for that load I'd want a minimum of ST225/75R15D tires which have 2,540 pounds weight capacity.

[plugugly]

thank you, that put it into terms i can understand with numbers. One of the better responses I have seen

[kampinguru]

Smokey;
You have some of the best responses when it comes to the towing limits of the truck. What I need to know, is, is the ratings that they put on the sticker inside the truck, the physical limits of the truck, or is that a legal limit before you need to go to commercial plates? I know that my rear axle weight is over the sticker limit by about 800lbs when I connect my 5ver. I need to know if I will run into issues from a mechanical failure, or a legal one with those weights. Thanks very much for you deep insight into a lot of issues with the trucks we all love. You have helped me significantly since I purchased the truck.

[SmokeyWren]

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What I need to know, is, is the ratings that they put on the sticker inside the truck, the physical limits of the truck, or is that a legal limit before you need to go to commercial plates?

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Physical limits of the truck. Set by engineers. As with most engineering specs, there is an unknown "fudge factor", or what automative engineers call a "safety factor", built into those numbers. So if your GVWR is 8,800, there is probably at least a few percent fudge factor that would allow you to go up to maybe 9,800 GVW before there is much danger of something biting you in the butt.

I suspect there is a much smaller fudge factor for the front and rear axle ratings. If your rear axle rating (rear GAWR) is 4,800 pounds, I would be very leary of putting much more than 4,800 pounds on that axle. And I would never overload the tires to more than the weight capacity on the sidewall of the tire.

"Legal" is defined by state legislatures, so it is different in every state. If you don't exceed Ford's weight limits, and provided you buy enough license plate to cover Ford's weight limits, you'll probably be legal in every state and province. But some states allow you to buy plates that severely overload the truck. As long as you pay for the plates, you can "legally" haul whatever those plates say - even if it is obviously unsafe and severely overloads the truck.

As to whether you need a commercial driver's license (CDL), I don't keep up with those rules. I know if your trailer grosses more than 10,000 pounds or your GCW is more than 26,000, you'd better check with your state DOT or driver's license beaureau to determine if you need a CDL.