QuestionQUESTION: I have 5.30-12 load range D tires on my boat trailer. The shop inflated them to max pressure, which I think is way too hard. The total axle weight is about 1200 lbs. What is an appropriate pressure for these tires?
Thanks
ANSWER: Robin,
The load carrying capacity of a 5.30-12 Load Range D is 1250# at 102 psi - so, No!, that would be way too high!
If what you told me is right, then you only need a Load Range B tire - max load 855# at 55 psi - for a total trailer weight of 1710#.
But I recommend you get the trailer weighed while it is hitched up to verify that value. be sure to make it a worse case by putting everything you can possibly think of that you would carry!
---------- FOLLOW-UP ----------
QUESTION: Thanks for your response. My problem is that I had to replace the tires, and load range D was all I could get where I live.
The 1200 lb axle weight was a scale measurement while hitched up. I say "about" to allow for load variations.
Is there a problem with running the tires at a lower pressure - say 30 psi or so?
AnswerRobin,
Trailers are a bit problematic:
1) Many folks only talk about the weight of the empty trailer - not considering that it is carrying a load in addition to its empty weight. It's also common for folks to only talk about the payload and neglect the weight of the trailer. The tires carry both!
2) Many folks talk about the weight as published by the trailer manufacturers - who are very bad about under-estimating how much weight their trailers actually carry.
For those 2 reasons, I strongly recommend you weigh the trailer fully loaded as described earlier.
- and here is where I am uncomfortable. It is SO common for trailers to be marginal for tire size, so I recommend using MORE inflation pressure than is required for a Load Range B (55 psi), just because of this is so very common. But 30 psi in that size does indeed carry 1200# - but I am afraid to recommend that. Just remember that a tire failure can cause a terrible accident and I don't want to be the cause of one.
