What is the maximum possible, load a typical 18 wheeler can carry

80,000 is max gross. To go higher you need a permit from the state you are operating in. Gordon and Interstate Distributors used to have a 3 axle trailer and it clearly said 88,000 on the cab. The trucks were licensed for more weight. Your 5 axle limit in your question is just 80,000 pounds and that's it. No one will let you go over 80,000, even with the spreads. That's just so you can haul more on the tail of your trailer, but the gross is still 80,000 without a permit.

BTW, weights differ in states, as well as the tolerance for overweight. Like California will let you go 200 pounds over on axle sets as long as your gross is okay. Also Calif allows 12,500 on steers, Louisiana is 13,000.

 

Hello Pedigreed Bulldog -

Thanks very much, that is exactly the type of information I am looking for and it makes sense to me. 113,000 lbs is 33 k over the legal or about 40%. This makes much more sense to me than 100% over load.

I appreciate your help,

Mike

 

Are you bothering to look at the weight ratings of most highway tires?

 

Thanks for the reply OFTOTR -

A number of years ago, the Texas State Legislature passed new rules which allowed Department of Public Safety weight enforcement troopers, when they stop a truck, to record tire rating(s) and compare these to their portable scales. This made it much simpler to tell if a wheel / axle group was overloaded compared to the old method of looking at pounds per inch of tire width.

I know that tire load capacities can vary significantly whether we are talking about an long haul truck or a work truck (dump, ready mix, concrete pumper etc.) Long haul trucks on the steer are perhaps 7500 - 8000. The tires on the tandems will be somewhat lower if they are dual tires more like 5000 - 6500; but each wheel position has two tires..... If a truck is running wide base singles, the load capacity must be higher of course.

In Texas, wide base tires are more common on fuel haulers and certain intrastate shippers who understand (in detail) the relationships between engine specs, truck speed, tire rolling resistance, wind resistance and fuel economy. You can gain about 4% fuel efficiency when switching to wide base tires - the dead load weight of a set of wide base tires and wheels is less than dual tires and wheels all around - so you get more cargo capacity to boot.

Fuel tankers who have to worry about roll over on curves - can take advantage of the narrower overall width of wide base tires by spec-ing a wider spacing between their chassis rails which allows them to lower the tank = lower center of gravity = lower roll over potential. I've attended ATA meetings as a member of the old Truck tire impact on pavement damage taskforce and heard testimony by major fuel tanker fleet managers who discussed this in detail.....the lower cg gave them the option of greater safety or more fuel hauling capacity = greater profit at the same level of safety.

We could add to these issues knowledge about the highway route since some routes will have more up and down grades - crest and sag vertical curves (including bridge approaches and interchanges in urban / metro areas.

Major rail companies know the track grades between different points along their routes and take this into account when computing the fuel consumption and wear on the locomotive and rail cars and in determining profitability. I'm not sure if long haul trucking companies do this....maybe the bigger fleets like Swift, Schneider, J B Hunt, Con-way etc.

UT-Austin and Center for Transportation research works with certain fleet operators in Texas to help improve their fleet efficiency.....and of course, we've looked at tires. Some fleet managers know which tires are best to run on each axle position (steer, drive, trailer) and know that tires wear at different rates in different Texas cities.

You wouldn't think tire wear would be that much different, but it is depending on the types of pavement surfaces (tined concrete, coarse surface treatments, dense graded hot mix, permeable friction course hot mix...etc. etc.). Our (UT-CTR) knowledge of the Texas network combined with their knowledge of their fleet adds up to lower maintenance and fuel costs.

Sorry for the long answer.

Mike

 

12.00R24 tires with a "J" load rating can carry 68,320 on a tandem.

445/65R22.5 tires with a load rating "L" would be good for 24,600 on the steers.

The equipment exists. It isn't common, though, because the more weight a tire is rated to carry, the higher the federal excise tax is on that tire. In other words, most companies buy tires rated close to what they need (typically the legal weight limit for their axles) because since they cannot carry the extra weight, it doesn't make sense to pay extra for a tire that is capable of doing work the law won't allow you to do. This is why "most highway tires" are only going to be rated for 6-7K single/5-6K dual. More than that and your stuck paying extra FET with zero increase to your legal payload carrying ability.

 

2011 Mack Granite (GU813) Roll off: factory gvw 39,000kg (85,800lbs)
Limited to 34,500kg (75,900lbs) by MTO....on four axles.....

10 tonne steer, 10 tonne lift, 20 tonne drives....

 

I once "saw" a 40 foot container that upon delivery, listed 125,000 of load INSIDE of it, so add the weight of the container, the trailer and the tractor!
I "hear" it was a dog to drive on the freeway!
BTW, this was decades ago during a southern CA fuel related strike, they all drove in convoy, the supervisor collected all the paperwork at the port, was the one to hand them over at the rail station so the drivers never got to handle it.

 

Some of this depends on the truck and what they haul. Many logging trucks here are rated well above the 80k limit. When I was in schooling for my CDL, our teacher informed us that some trucks were rated to haul gross of 140k

 

My father was involved in working with the Civil Defense organization for the county and they would get surplus military stuff for the county.

They had a mobile field hospital in a 1930 single axle trailer set up to be pulled by an old army [white] single axle gas job. all on those funny lookin military lug tires.

They had to get the weight of the hospital so they took it up the street to the local scrap yard. The loaded trailer weighed 109,000#....

I guess they don't build them like that any more!