'Clyde the Ride' Got New Shoes
 

Couldn't stand the vibration....and the edges were gone and the wear bars were almost exposed
https://lh6.ggpht.com/_4xQFBZJE2fI/St...0/DSC01727.JPG
so, unlike my normal habit of waiting for the rains and the metal to start peeking from the sides of a tire, I replaced the BF's with Michelins.

Got a set of LTX/MS2 and decided to try and improve my MPG by going from the stock 265/70X16 to 265/75X16
Whoa!
drives like a totally different truck!

Gone: JATO acceleration. Gone: Glancing in the mirror, seeing nothing but the Freightligner logo and deciding, "no problem" and smartly pulling away.
Gone: The easy running through the gears to 5th by 30 MPH.

Had to re-learn hiking by butt in and out of the seat.
Now the shifting is more akin to the pattern of a 4-speed and I noticed the tach needle at places it never was before,
now going to 2,500 and 3,000 RPM shift points as it stays in gear longer.

Ran a test.
Set the cruise, so I'd have lots of time to verify the speedometer against the GPS and at 5 mile increments from 25 MPH through 70 MPH, the difference was 2 MPH.
https://lh4.ggpht.com/_4xQFBZJE2fI/St...0/DSC01744.JPG
I think I'm safe thinking that the truck now is 2 MPH faster than the speedometer reads. No problem learning to set the cruise differently. I'll learn to live the lie that I really went further than the odometer says.

BUT

What I want is to figure my mileage accurately. The numbers still come out the same as before, but I really drove further than the figures I'm using.
Accepting math help.




Reciept from America's Tire

4 LT265/75R16E1 W Michelin LTX M/S2 ORWL ............... $213.00 .... $852.00

4 Free replacement Certificates .................................. $032.00 .... $128.00

4 State Required Environmental Fee ............................ $001.75 .... $007.00

4 Lifetime spin Balancing ............................................ $015.00 .... $060.00

4 Lifetime Rotation and Repairs ................................... $000.00 .... $000.00

4 TPMS Rebuild Kit .................................................. . $007.00 .... $028.00

Sub Total .................................................. ............................. $1,079.00
Arnold and the Democrats .................................................. ........ $0,081.77
Total .................................................. .................................... $1,160.77

The real question is, why are they wearing on the side(s)? Are they wearing on just one side or on both sides? An alignment can help with your fuel economy since it would reduce rolling resistance of the vehicle.

i feel for you my friend. quality, new tires and alignment only set me back ~$300.

You need more pressure.

The math is easy. Just adjust the miles before you compute MPG. Since you only bought 4, you can still do a rollout test with weight on the truck; put the spare on and measure tire circumference on both sides of that axle by rolling it until you get exactly one revolution (use paint or whatever you want to make it easy). You can get the percentage difference and adjust your mile by that percentage.

Less effort and more accuracy, though, would come from just using the GPS. Reset its trip odometer and your truck's trip odometer in the morning then check them at the end of the day.

1. I let the boys at America's Tire Store handle the pressure. They helped me get 163,000 miles out of the last Michelins. But I'll check with Michelin. These are 5 Ply and different than the stock size.

2. Truck is aligned. I bought a lifetime alignment package from Firestone for the cost of 1 1/2 alignments, and I do it every 5,000 to 10,000 miles. They have lost a lot of money on me over the years.

3. The edge wear, inner and outer, is not terribly abnormal for tires with 77,000 miles on them.
They told me the little bumps that were causing the vibration came from not rotating often enough.

4. Calculate using percentages? Hah! I have enough trouble calculating MPG.
I tried the GPS, but I have to get in touch with Garmin and ask how accurate the odometer is. I have the newest software and maps but I don't completely trust it because it used to be way different than the truck odometer before I got the new tires.

The slightly larger tires will call for slightly lower pressure compared to what was right for your previous tires. Your previous tires were definitely too low.

I hope employees at America's Tire Store are smarter and care more than employees at every place I've ever bought different-sized tires; I've never had anyone check a load-inflation chart, do any kind of calculation, or otherwise put any thought or effort into recommending pressure for new tires or to solve a problem.

If calculating with percentage doesn't work for you, you could do the calculation once for your usual fillup mileage and just always add that amount. So if you usually fill up at 400 miles, and the percentage calculation means adding 10 miles, you could just add 10 miles every time.