I wanted to ask our weighing expert a simple question? Even though my rig tows level, I have seen numerous rigs on the road that have a serious high hitch. Now, since we all have "equalizing wheel systems" do these high front rigs put undue weight on the rear tires? I realize the equalizing axles can and will do a bit of weight distribution, have you seen any effect on the tires due to this condition? Just an idle mind at work.
Howard said
01:20 AM Sep 26, 2012
Yes, the high front ends do shift extra weight to the rear tires. It only takes fractions of an inch to shift weight. You would be amazed at how much the weight distribution changes with an adjustment up or down one hole on the hitch or on the kingpin.
Towing a fifth wheel "nose high" can shift too much weight to the rear tires and axle. It can cause overloads in what would otherwise be a properly balanced rig if it was towed level. In addition, it can reduce fuel efficiency as the trailer doesn't "draft" as well and too much weight on the rear axle causes additional "drag" because the weight isn't properly distributed among all four tires.
There are other potential consequences of nose high towing such as undue upward pressure on the hitch and the lack of proper vertical load (pin weight) on the rear axle of the truck. This can also cause the trailer axles and tires to be overloaded since more weight should be on the truck (20 - 25% of the trailer's total weight should be on the truck).
This is becoming more and more of an issue as truck beds (and rails) are getting higher and fifth wheel manufacturers aren't making adjustments. Many new fifth wheel purchasers are finding that the clearance between their truck rails and the fifth wheel isn't adequate forcing them to use the highest setting on the hitch causing them to be nose high or run the risk of damaging the truck rails when turning.
It's very important to measure to accomplish both goals of good clearance between the truck rails and fifth wheel (6 inches minimum) and to match the hitch height with the kingpin to tow as level as possible.
Excellent question, Ken.
53 Merc said
01:52 PM Sep 26, 2012
Yeah, your findings match my "seat of the pants" assumptions. I guess all that means is I gotta keep my '04 truck, because I have adequate rail clearance and my rig sets level without adjusting the trailer axles. Oh well, the truck is paid for. Some of those new ones are really nice though.
I wanted to ask our weighing expert a simple question? Even though my rig tows level, I have seen numerous rigs on the road that have a serious high hitch. Now, since we all have "equalizing wheel systems" do these high front rigs put undue weight on the rear tires? I realize the equalizing axles can and will do a bit of weight distribution, have you seen any effect on the tires due to this condition? Just an idle mind at work.
Yes, the high front ends do shift extra weight to the rear tires. It only takes fractions of an inch to shift weight. You would be amazed at how much the weight distribution changes with an adjustment up or down one hole on the hitch or on the kingpin.
Towing a fifth wheel "nose high" can shift too much weight to the rear tires and axle. It can cause overloads in what would otherwise be a properly balanced rig if it was towed level. In addition, it can reduce fuel efficiency as the trailer doesn't "draft" as well and too much weight on the rear axle causes additional "drag" because the weight isn't properly distributed among all four tires.
There are other potential consequences of nose high towing such as undue upward pressure on the hitch and the lack of proper vertical load (pin weight) on the rear axle of the truck. This can also cause the trailer axles and tires to be overloaded since more weight should be on the truck (20 - 25% of the trailer's total weight should be on the truck).
This is becoming more and more of an issue as truck beds (and rails) are getting higher and fifth wheel manufacturers aren't making adjustments. Many new fifth wheel purchasers are finding that the clearance between their truck rails and the fifth wheel isn't adequate forcing them to use the highest setting on the hitch causing them to be nose high or run the risk of damaging the truck rails when turning.
It's very important to measure to accomplish both goals of good clearance between the truck rails and fifth wheel (6 inches minimum) and to match the hitch height with the kingpin to tow as level as possible.
Excellent question, Ken.