17.5 tires

mpierce wrote:

bucky wrote:
Dropping the pressures is hard on your fuel mileage, the trick is finding the best compromise.

Not really. Point is, if using 16" tires, and need 80# to hold the load,then you go to 17.5, you still probably only need about 80# in them to hold the load. NOT the 125# that they are rated for.

Putting 80# in the 17.5 will yield same mpg as 80# in 16", and be a softer ride than running them at 125#. And, at 80#, the 17.5 is a stronger, tougher tire carcass.

Not really.
I've found those heavier carcass G tires run hotter with much more parasitic drag (rolling resistance) using only 80 psi in them.
I tried that silly trick of over tiring my small 5 trailer fleet of GN /enclosed trailers with higher G load range tires and run 80 psi in them even after my truck tire dealer suggested not to. I found out the hard way he was right.

Tireman9
rvtiresafety.com


The question of load capacity and Load Range gets asked a lot, so it seems to be a bit of a stumbling block for a number of RV owners. Here is an example:
"I need to replace the ST235/75R15 tires on my trailer. Currently have load range C tires which is sufficient for the maximum trailer weight when inflated to 50psi but allows almost no safety margin. I want to change to either load range D or E tires. My rims are only rated for 65 psi so if I went to the load range E tires I would only be able to inflate them to 65 psi. My question is this. Is there any advantage to a load range E tire used at 65 psi vs a load range D tire at 65 psi?"

Now just because he is asking about a 15" trailer application and considering a change from LR-C to LR-D it does not mean the general answer does not apply to others, even if they are considering a change from LR-G to LR-H on a Goodyear 295/75R22.5 Class-A tire.
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The answer to the question is;
He will gain a safety margin if he increases his inflation to 65psi with LR-D but if he stays at 65psi there is nothing further gained by going to LR-E as there is no difference in the capacity at 65psi.
The same thing would apply to the 22.5 example. When we look at the Goodyear tables we see that at 110psi both the LR-G and the LR-H are rated for 6,175# single or in dual application at 100psi they both are rated as 5,675#.

Special note: It is important that you look at the table on the web site of the manufacturer of your tires as not all companies give the exact same capacity number at every inflation level, even for the same size.