How to Select Trailer Tires with Correct Load Range Rating for Trailer Gross Weight

Question:

Hi, I understand that trailer tires have designated load ranges. What I do fully understand it exactly what that load range means. For example if a trailer tire has a 1300 lb load range capacity, does that mean if you had a trailer with 4 tires two axles the maximum weight of the trailer should not exceed 5200 lbs? 4 x 1300= 5200? In other words, If I had a trailer that has a gross loaded weight of 4000 lbs, each of the 4 tires would have to be load rated for at least 1000 lbs or more? Thank you.

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Expert Reply:

Your math is correct in your trailer weight load example. If a fully-loaded tandem axle trailer weighs 4000-lbs then each of the 4 tires will bear 1/4th of that load, or 1000-lbs. In this case a tire rated for 1300-lbs would provide a good safety margin. A tire's rated Load Range means the maximum weight load it can handle (when installed on a suitably-rated wheel) at its full rated PSI pressure.

Trailer tires must always be fully-inflated to their maximum rated pressure as noted on their sidewall. Only when fully-inflated to that maximum psi pressure can a trailer tire deliver its rated weight carrying capacity.

The wheel/tire you referenced, Kenda 4.80-12 Bias Trailer Tire/Wheel # AM30660, combines a steel wheel rated for 1250-lbs with a Load Range C tire that itself is rated for 990-lbs at 90-psi. Since the tire is rated lower than the wheel, the lower rating determines the overall capacity of this item, 990-lbs.

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Adam R

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Follow up Questions

David M.

I found a second eTrailer page that has a chart which states the tires on my trailer will support D rating of 2,540 lbs at 65 psi. So that’s makes me feel much better but 2540*4=10,160 still doesn’t support the 12,000 GVWR of the trailer. Is there some kind of demand factor used? I find it hard to believe a company like Hudson Brothers would install underrated tires on their trailers. What’s up? 98612

Reply from Jon G.

@DavidM Make sure that you are checking the weight rating of the exact tires on your trailer as that can vary some between tire manufacturers. Another thing to keep in mind is that there is the tongue weight of the trailer to look at since this load will be directly placed on the vehicle. Your best bet is to look at the weight rating of your axles and make sure that your tires are rated for at least that much. In all honesty it wouldn't be the first time we've heard of a trailer company saying one rating and then putting equipment on that doesn't quite add up. That's a question you'll have to ask your trailer manufacturer though just to be on the safe side of things. 73422

Reply from Jon G.

@DavidM Make sure that you are checking the weight rating of the exact tires on your trailer as that can vary some between tire manufacturers. Another thing to keep in mind is that there is the tongue weight of the trailer to look at since this load will be directly placed on the vehicle. Your best bet is to look at the weight rating of your axles and make sure that your tires are rated for at least that much. In all honesty it wouldn't be the first time we've heard of a trailer company saying one rating and then putting equipment on that doesn't quite add up. That's a question you'll have to ask your trailer manufacturer though just to be on the safe side of things. 73423

Reply from David M.

@JonG No D rated tire I can find adds up, so I'm betting there is some demand calculation they use. I find it difficult to believe Hudson Trailer company puts inadequate tires on their trailers. I'm definitely going to check with them though. I asked the dealer about this and they just said "don't worry, it will be ok". LOL Interestingly, even if using E rated tires I can find none that have a 3000+ rating which is what it would take (4, 3000# rated tires) to support a max trailer GVWR of 12,000#. Thanks for the followup Jon! 73425

David M.

Ok, I just ordered a 5 ton Hudson trailer. (12,000 GVWR; trailer 2k, max load 10k) It comes with four ST 225/75 R15 8-PR tires. D rating = 1220 lbs. per another eTrailer web page. In the context of the above my trailer and load cannot exceed 4880 lbs.?!!? Seriously?? 1220*4=4880 lbs. allowable GVWR because of tire rating. Trailer weighs 2000 lbs. Means the largest weight I can haul is 2880 lbs??!? That can’t be right! 98611

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