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After returning from a 7k mile RV trip, towing our 17k lbs 5th wheel, the outer tread bands of the steer tires on our F450 are basically bald. Both left and right front tires. Rears are fine.
Had an alignment done about 10k miles ago.
On a McPherson strut design passenger car, when unloading the front suspension, the camber goes more positive which also causes toe in.
Does the same thing happen with the suspension geometry on a 450? More positive camber and more toe in would result in more outer edge tire wear.
If so, is there such thing as a towing alignment to accommodate the rear squat and the subsequent front suspension unloading when towing heavy?
After returning from a 7k mile RV trip, towing our 17k lbs 5th wheel, the outer tread bands of the steer tires on our F450 are basically bald. Both left and right front tires. Rears are fine.
Had an alignment done about 10k miles ago.
On a McPherson strut design passenger car, when unloading the front suspension, the camber goes more positive which also causes toe in.
Does the same thing happen with the suspension geometry on a 450? More positive camber and more toe in would result in more outer edge tire wear.
If so, is there such thing as a towing alignment to accommodate the rear squat and the subsequent front suspension unloading when towing heavy?
Or maybe my tire wear isn't related to squat...
Assuming you have slight toe-in unloaded, a solid front axle won't drastically change the scrub angle or toe.
If the tires are that heavily worn on the outside edge, I would think the truck would want to wander unloaded and especially rear loaded when towing.
If you have different wheels, perhaps you changed the scrub radius and are wearing your tires out when turning?
Get your rig on a scale fully loaded the way you travel and see what the front axle weight actually is. The geometry of a solid axle allows a negligible amount of toe in and camber out (positive) when weight is taken off the axle. At least to me it sounds more like you have quite a bit of front axle weight and the tires are taking a beating through cornering. Driving style, hard cornering and or braking through corners at speed will also wear the tires like you've described.
After returning from a 7k mile RV trip, towing our 17k lbs 5th wheel, the outer tread bands of the steer tires on our F450 are basically bald. Both left and right front tires. Rears are fine.
Had an alignment done about 10k miles ago.
On a McPherson strut design passenger car, when unloading the front suspension, the camber goes more positive which also causes toe in.
Does the same thing happen with the suspension geometry on a 450? More positive camber and more toe in would result in more outer edge tire wear.
If so, is there such thing as a towing alignment to accommodate the rear squat and the subsequent front suspension unloading when towing heavy?
Or maybe my tire wear isn't related to squat...
Camber doesn't change on a solid axle as the suspension works.
Outer only tire wear on both fronts just sounds like too much toe-in.
I'd take it back to where you had it aligned and get them to check it for you, make sure it is in factory spec.
If they verify that, then maybe have them adjust the toe to the outside just a small amount.
I would imagine any good front end shop will have plenty of experience to judge how much to change the toe setting.
Are you running the factory Continentals? I think it's common for these tires to do this fairly quickly. Mine were showing significant wear by 5k miles. I saw another 450 at the campground his tires were as you described and he had like 10k miles on his. I sold my factory tires and went with something different.
Properly set up a 5th wheel removes and adds no weight to the front axle. What does change though is the angle of the frame, which in effect can cause toe to increase. When aligned empty, the Caster is at spec, when you load the truck and drop the frame a few inches with the 5th wheel, the caster increases positive, which in turn pulls the toe. BUT, it goes toe out, not in. Even so, it would not change enough to cause excessive wear, and it if did, it would be the inside of the tire.
I suspect the issue is not alignment,but the truck being an F-450 to be the issue. When you turn sharp, especially with a load behind, it will cause excessive outer tire wear. The F-450 is one tight turning SOB, so that could very well be the cause of the tire wear.
Properly set up a 5th wheel removes and adds no weight to the front axle. What does change though is the angle of the frame, which in effect can cause toe to increase. When aligned empty, the Caster is at spec, when you load the truck and drop the frame a few inches with the 5th wheel, the caster increases positive, which in turn pulls the toe. BUT, it goes toe out, not in. Even so, it would not change enough to cause excessive wear, and it if did, it would be the inside of the tire.
I suspect the issue is not alignment,but the truck being an F-450 to be the issue. When you turn sharp, especially with a load behind, it will cause excessive outer tire wear. The F-450 is one tight turning SOB, so that could very well be the cause of the tire wear.
I believe that hits the nail squarely on the head.
I would have the alignment double-checked. Rotating the front tires might help. Taking them off the rims to rotate would be even better. Or, maybe buy one new one for the front and use the spare for the other. That doesn't solve the problem, but would allow you to start fresh on the cheap.
You also might consider a different tire for the steer axle. Many folks have had bad experiences with the Conti's on the front. So far, mine have been okay (about 15K miles with about 2/3rds heavy towing of a tag and 5'er).
Truck tracks straight and true both loaded and unloaded.
I should mention that they are the original wheels with original Contis, with ~50k miles on them.
Truck was checked and was within factory alignment specs about 10k miles ago (was not out of alignment previously).
Oh, 50K on the tires is different. I would double check alignment is correct and buy new tires. I know they say 19.5's run super high mileage, but drive tires on a steer axle typically don't.
Properly set up a 5th wheel removes and adds no weight to the front axle. What does change though is the angle of the frame, which in effect can cause toe to increase. When aligned empty, the Caster is at spec, when you load the truck and drop the frame a few inches with the 5th wheel, the caster increases positive, which in turn pulls the toe. BUT, it goes toe out, not in. Even so, it would not change enough to cause excessive wear, and it if did, it would be the inside of the tire.
I suspect the issue is not alignment,but the truck being an F-450 to be the issue. When you turn sharp, especially with a load behind, it will cause excessive outer tire wear. The F-450 is one tight turning SOB, so that could very well be the cause of the tire wear.
Running over the scales it looks like I add about 100lbs to the steer axle when hooked up to my 5er.
Once getting to the mountains on our trip, there definitely was a lot of loaded tight turns, both up and down.
It is a tire issue. The front tires should be a steer tire, not a drive tire.
These continentials are not designed for the steer.
I ran 33K miles on my steer tires and them changed them out. I kept them for the inner rears later since they are still good on the main thread area and will pass DOT standards.
Roadmaster tires on what I am running now for the steer tire. These are a cooper tire. at 33K on the old tires
It is a tire issue. The front tires should be a steer tire, not a drive tire.
These continentials are not designed for the steer.
I ran 33K miles on my steer tires and them changed them out. I kept them for the inner rears later since they are still good on the main thread area and will pass DOT standards.
Roadmaster tires on what I am running now for the steer tire. These are a cooper tire.
at 33K on the old tires
Now that seems to make sense, but I am running the older HSR which is considered an "all position" tire, so it's not dedicated drive.
Either way, I am gathering here that the fact that I was able to get 50k miles out of them suggests I most likely don't have an underlying issue.
