I have E rated Pirelli Scorpion Tires. Should I keep them at 80 PSI even for town driving or should I drop them to 50 in front and 55 in rear? Will I lose mileage by that or not?

 

The higher the pressure the better your mpg's. Also, the bumpier the ride and maybe uneven wear on the tires.

I run my mine at 70 all the time and they are wearing fine and I don't mind the bumpier ride (it's a truck). The tires that I have are BFG all terrains (E rated).

 

if you go to an advanced auto and ask for a tire guage they should give you something that would let you see how the tires are wearing by measuring the amount of tread you have left. It'll take a couple miles of treadwear to give you a significant reading. If the tires have lower in tread outside than inside, pressure is too low, if the reverse, pressure too high.

If the measurements of the tire (### ## R##) is the same as your old ones, then run them the same pressure to start out.

 

Reason I am asking is that since I am not towing now, if I lowered the pressure to 50 front and 55 rear like the sticker says, will I lose MPG? Of course, when I tow, I will bump it back up to 80 psi. Has anyone noticed a significant MPG difference between 50-55 and 80? I gusss what I am asking is where the breakpoint is. The higher the pressure, the better the MPG. However, at what point will you reach deminishing returns? Is 70 the magic number?

 

The magic number for me was being able to ride down the road with it being comfortable. Aired mine up to 65psi and left it. To me it's too much trouble raising/lowering the pressure depending on whether you're towing or not. Experiment with different settings and different driving/towing situations and find what you like best and leave it. Just my .002

 

I found 55 front/50 rear to give the best wear. If you are running empty the front is much heavier than the back. But then again I have 285s on the stock rims.

 

you may get better mileage with higher pressures, but you're gonna wear the tire out quicker, and diminish its ability to grip the road. Towing dosen't require more pressure, if you overinflate the tires and load them up with a trailer or lots of stuff in the back you're just as likely to blow one as if you underinflated them and loaded them. Keep them where they wear the best, and the rest will take care of itself.

 

I thought the sidewall of the Scorpions say 80 psi max. What should I set it at when I tow my 8500-9000# Toy Hauler?

 

I would air up the rear to 80 since you will be near the rated capacity. I can't tell you what that is since mine came with Ds and has the D sticker.

 

What about the fronts then? I would think that you have to do the fronts since I will be using a weight equalizing hitch which, if it understand spreads the load among 4 tires.

 

80 might be a little extreeme on the front.

 

So what is your recommendation? 80 in the rear and what in the front? I thought the hitch was supposed to spread the load. Not doubting you but I have never towed something that heavy and I don't want to find out the hard way. I'd rather get a cheap answer out of you all than to get the expensive answer from the tow truck when I blow my fronts. TIA

 

Are you using a weight distributing hitch?

 

I tow. Looking at different manufacturers specs for tires and inflation, I found that the Ford recommended tire pressure provided adequate load for the GVWR of the Excursion.

Now, 45 front and 50 rear seemed a bit low. The tires looked low!!

I was looking into this because I was trying to find out what was making my Excursion have wander, an I wondered about the tires.

I found that the lower the pressure, the better the ride, but the sidewalls flex more and more.

With factory recommended air pressure, I extended my tow mirrors and turned them down where I could see the rear tires. I went out on the highway and local roads,

Sure enough, sidewall tire flex was prevalent. I hooked up the trailer and found that it did even worse.

No wonder it was wandering.

So, I did some experimenting over the next few days, and found that as little as 10 lbs extra helped a lot. 55 front/65 rear psi for me was the magic number.

This si something you should experiment with. Use the lowest air pressure that will give the sidewallls enough tension that they don't flex all over the place. You may end up with two set of numbers that you are comfortable with, one for towing, and one for normal driving.

 

By the way, putting the extra pressure in the tires removed at least 80% of the wander.