Tires: RV Tire Inflation Pressure, proper inflation pressure, tire inflation

Question
Barry, thanks for the response.  My vehicle placard says 58 psi for the original Load Range D tires.  I'm not increasing my vehicle load above the GVWR.  So if I understand it, I should inflate to 68 psi.  Since the new tires allow for load/inflation for 80 psi is there any advantage (e.g., better mileage, less wear) or disadvantage (e.g., loss of handling, safety in rain) to increasing the inflation to 75-80 psi, even though I'm not near the GVWR?  I appreciate your help.
Steve
-------------------------

Followup To

Question -
How do I determine the correct pressure for new tires on my motorhome?  I have upgraded to Load E (from Load D).  The tire says load 2680lbs 80 psi cold, but my load is only 2100 lbs/tire.  Should I still inflate to 80 psi, or a lower pressure.  The tires are Cooper SRMII LT215/85/R16 LR E.  Thanks!
Steve

Answer -
Steve,

In theory, there shouldn't be any change in inflation pressure from changing from a Load Range D to Load Range E.  The load carrying capacities are the same for a given inflation pressure.

However, why not take advantage of the additional capacity the Load Range E's provide.

Somewhere on your vehicle is a placard that lists the original tire size and the proper inflation pressure for that size.  I would use 10 psi above that value.

Answer
Steve,

There are several advantages to using a tire with more load capacity - which is the net effect of using more inflation pressure.  You'll get better fuel economy, better tire wear, better tire durability, better wet traction, better snow traction, and will only give up a bit of ride harshness.

Just as background - these vehicles are kind of notorious for being marginal on tires.  One of the lessons from the Ford / Firestone situation was that oversizing tires was a good thing.  Cars generally were oversized a bit while pickup trucks, vans, and SUV's weren't.  So most of the vehicle manufacturers have increased the tire size in the last few years - both both cars, but especially for SUV's and trucks.  The vehicle manufacturers have also started specifying higher speed ratings - which is also one of the lessons learned.

However, I should point out that the vehicle manufacturer never concieved that we'd be oversizing the tires by using more inflation pressure, so the springs, shocks and sway bars were set up with the lower pressure (less stiff) tires.

If I were you I wouldn't use more than 10 psi above the placard.