Tireman9 wrote:
Great_Danes wrote:
OK... so I read through the majority of posts on this thread and there is definitely a lot of good information here!!
The only thing I am a little unclear about is how the load ratings are calculated between ST and LT tires. I am in the process of researching new tires for my 5er and have found that the Goodyear G614 (LR-G, 14 ply, 3750lb capacity, LT tire) would meet my criteria. One of the shops I spoke to also recommended a Kenda Karrier HD Radial (LR-F, 12ply, 3960lb capacity ST tire).
I am confused as to how a LR-F tire can have a higher max laod capacity than a LR-G tire even if they are ST vs. LT. Obviously the Kenda is about 1/2 the cost of the GY. My trailer axles are rated (according to the placard) at 6840lbs but I know they are 7k axles that the manufacturer reduced the rating on to ensure that the standard LR-E tires (rated at 3420lbs) can be used.
And to top it all off, I found I can upgrade to a 17.5" tire (Hercules H-902 245/75R17.5 135/133L 16 ply) including new steel rims for the same cost as the G614. I am leaning towards the 17.5" option because it seems the tires are more readily available than the G614 (at least around here) and of course because the load rating is total overkill for my trailer at 4805lbs per tire. Also, the replacement cost of the 17.5" tire is about $100 less per tire than the G614, so in 5 years when I need to replace tires, my costs will be less.
Does this logic make sense, or am I going way overboard here when I could safely go with the Kenda tire in terms of load capacity and in turn save a whack of dough? Comments?
Others have and will suggest you consider the 17.5 option. I think you have considered the details as long as you confirmed all the components such as axles, springs, hubs, wheels etc.
RE LT load limits vs ST Load limits.
Ther is no direct simple factor to convert load/inflation tables from ST loads to LT loads. ST tires have higher rating becsuse they have shallower tread depth (cooler running), A lower speed limit 65 vs 75 or higher for LT and ST type are intended for Trailer use only in Highway Service. I know of no state that allows people to travel in trailers while in motion so would interpret this to mean not intended to transport people.
And if you go way back through this thread you will see where we discussed the "K" factor. It is a variable in the equation for computing the load capacity of a tire and is related to the severity of the expected service of the tire. The K factor is different between ST tires and LT tires such that if you had two tires of identical construction, size, and inflation pressure, the one that is designated an ST tire will have a higher load rating than the one designated LT. This is because they think a trailer tire has a cushy life compared to a tire on a truck.
Your conclusions about the 17.5 inch upgrade is the same as many others -- and those that plan on keeping their units long enough to go through at least two more sets of tires have chosen to do it for both the economics of it, the serviceablity out on the road, and the reliability of the products.
