Tire and Axle Capacity of Trailers

There are many different types of axles and tires in the trailer world and there always seems to be questions on how big tires and axles need to be. Here are a few guidelines to help you determine this. These calculations are only to help you have a rough idea on how to determine these values. Always refer to the manufactures exact specifications on tires, axles, rims, and trailers before purchasing or pulling any trailer.

1. Empty Weight of the trailer is your starting point. If the manufacturer does not have a published weight of the trailer, you can click here to learn of a few simple formulas to estimate horse trailer and livestock trailer empty weights.
   
   
2. Cargo Weight will then need to be determined, the amount of weight you plan to carry with this trailer. This will not only include livestock weights but remember to figure liquid (water and gas weigh approximately 8 lbs/gallon), saddles, hay, feed, tack, carts, and anything else that might be transported with you trailer. On living quarter trailers, verify the empty weight does include the weight of the conversion.
   
   
3. Gross Loaded weight. Add trailer empty weight (#1) to cargo weight (#2) to determine gross amount trailer will weigh when loaded. You can then determine (approximately) how much weight should be distributed to the neck of your trailer to your vehicle as well as the axles/tires. This weight distribution can vary widely based on axle placements and construction of the trailer but generally gooseneck trailers will have 20-25% of the gross weight on their neck and 75-80% will be on their axles and tires. Bumper pull trailers generally have 15-20% of gross weight on the tongue of the trailer and 80-85% on the axles and tires.
   
   
4. Axles. Depending on the number of axles you have (1-3 normally), you will then divide the weight distributed to your axles/tires by the number of axles. For example: If your trailers loaded gross weight is 10,000 lbs, 80% will be on your axles/tires or 8,000 lbs (10,000 lbs x .80). If 2 axles are present, then each axle will carry 4,000 lbs. This means that any axle over a 5K (5,000) rating should be sufficient. Having axle ratings much heavier than actual weight hauled is acceptable, however, they will be much stiffer and result in a "bouncier" trailer if considerably heavier than needed.
   
   
5. Tires. Since there are twice as many tires as axles, you can divide in half (divide by 2) what each axle is carrying to determine how much weight will be on each individual tire. From the example above, you would take the 4,000 lbs/ axle and divide this by 2. Each tire would need to have a carrying capacity of 2,000 lbs / tire to handle this load. All tire manufacturers have a little different weight ratings, inflation suggestions, and speed capacities but here is a list of standard weight capacities generally accepted in the tire industry:
   • 10 Ply (E Rated) 3,042 lbs/tire
   • 14 Ply (G Rated) 3,750 lbs/tire
   • 16 Ply (H Rated) 4,410 lbs/tire (9R 17.5" radial tires)
   • 16 Ply (H Rated) 4,805 lbs/tire (215-75R17.5" low profile tires)
   • 16 Ply (H Rated) 5,530 lbs/tire (11R 17.5" radial tires)
     
     ** for maximum life and optimum performance of your tires, always follow the recommended tire pressure listed on the side walls of your tires.
     
     
     

Final Note. Again, these are strictly estimates and we stongly encourage thorough research from manufacturers of tires, wheels, axles, and trailers when purchasing or pulling any type of trailer.