Re: 2 trailers questions: tires *yawn* and alignment
I've been doing a lot of reading since the last post and getting much conflicting info but I'd thought I'd share some of it here and see what you think. <br /><br />Seems like there is consensus that light truck and trailer tires do have stiffer sidewalls. But what is not clear is if this stiffer sidewall is what allows for higher inflation pressure which in turn allow for greater loads. If the tire is rated for the load it is carrying, some state it doesn't matter if it is ST, LT or P-Metric. <br /><br />There are many posts of people stating they have spoken with 'experts' or engineers that state using a PX tire on a trailer is fine ( as long as it is load rated ), but NEVER an ST tire on a car. There are just as many that state that they have been using passenger tires on their trailers since forever without a problem but have seen plenty of blowouts, defective tires etc. with ST Tires.<br /><br />Px tires, i.e. radials, are superior in every way to bias ply except for sidewall stiffness such as quietness, comfort, longevity and fuel economy. The stiffness of a trailer tires is req'd because of the added load and stress. But I ask: what added load and stress? Assuming the tires carry the equivalent weight, wouldn't the stresses of acceleration, braking and especially corenering be far more on a car than on a trailer?<br /><br />It seems conclusive as well that max. load has a lot to do with max psi. The sidewall stiffness is just what allows for higher psi. What I dont quite understand is how a passeneger tire of the same dimensions as a trailer tire but only a max psi has the same load rating as a trailer tire with higher psi tolerances.<br />This is a consideration for me for two reasons. I have noticed that my trailer tires seem to look under-inflated, even when filled to the max psi. This is especially true when I see how they absorb a bump. However, even with my over loaded trailer, they still are well within maximum load limits. I have read that going from a ST tire to a passenger tire on a trailer allows the load to sway more easily. This makes sense if the sidewalls are stiffer on an ST tire. On the other hand, my boat does seem to sway easily on its trailer tires when I compare it to my utility trailer that weighs about the same that I have been using used car tires on for the past ten years. <br /><br />None of what I have read has mentioned anything about profiles or series. I know from buying tires for a sports car how important sidewall stiffness is and when I have gone from S or T rated tires to H rates tires, the difference in cornering is unmistakeble. The sales people tell me this is due to stiffer sidewalls. I have also been told that a lower profile will do this - which makes perfect sense when you look at how thin sports car tires are. <br />So, what are the pros and cons for changing the series of a tire on a trailer. How does the mfg. decide? <br /><br />All I know is that ST tires will cost me more than twice as much as a decent car tires and the more I think about it, I cannot see how a car tire that is rated for the same loads can possibly be a disadvantage or liability over ST tires given that a car tires should give the trailer a smoother ride, last longer and save on gas. But I remain open-minded. Is there something I am missing?
