Hypermiling - I'm Getting 28.8 MPG

[pokismoki]

more so on the front tires, under inflated does cause a wear on the outside edge, pumped up more keeps tire more square and off the sidewall in corners

[redwngr]

[Wiggums]

13 hours ago, redwngr said:

 

I'm aware of that.. I'm assuming it's like 60 psi on a 35 psi tire. My tire says 35psi and I'm reading from others it's fine to do 40 psi as well. Temperature is consistent around here so I don't worry about heat causing it to swell. Do they put 35 psi on the tire expecting it to hit 40 during the hot summer months so it's actually 40 but they don't want to get too technical?

[Grumpy Bear]

I'd tell ya but no one would believe me so buy it and read it....

 

https://www.sae.org/publications/technical-papers/content/800087/

 

 The radial tire is less sensitive to load and pressure variations; ... Bias-Belted and Radial Tire Performance," SAE Technical Paper 800087,

[pokismoki]

1 hour ago, Wiggums said:

 

I'm aware of that.. I'm assuming it's like 60 psi on a 35 psi tire. My tire says 35psi and I'm reading from others it's fine to do 40 psi as well. Temperature is consistent around here so I don't worry about heat causing it to swell. Do they put 35 psi on the tire expecting it to hit 40 during the hot summer months so it's actually 40 but they don't want to get too technical?

well i keep the front at 40 to start with, so driving makes it pump up to about 45psi, i leave the rears at 33-35, they aren't really doing the hard work like the front tires

[Grumpy Bear]

Just my personal experience with the K2** (running all season standard load rating not all terrain or E type). Under 35 psi (cold) mileage drops pretty quick. Above 35 psi there is a slight difference but not one I've been willing to trade for ride/wear/tear. And I mean wear/tear on the rest of the truck not the tires. Shock....

 

Tire pressures will increase a few pounds with running (roughly 8-10%) and about a pound more per 10 F rise in ambient temperature. In a pickup with a dead rear axle (no toe or camber) the fronts, on long hauls, will run about a pound higher than the rears and the drivers side front the highest of the bunch but not more than a pound more than the passenger front. Less noticeable on Interstates. More so on State highways with crowns. You can even get a 1 psi difference between the sunny side and the shady side going down the road at mid day middle summer. 

 

Monitor you TPMS awhile. It's an education worth the price of attendance.  

 

 

[redwngr]

Recommended tire pressures are always for when the tires are cold. 

 

Believe it or not, tire manufacturers and auto manufacturers know that tires get warm and pressure increases when they are drive.  (duhh...)

 

They account for this in the recommendation. 

It would be really tough to ask an owner to check the tire pressure when the tire temperature was at, well, any temperature other that 'cold'.

 

As Grumpy points out, tire pressure sensors work when tires are 'cold' as well as when 'warm' after being driven.

 

Tire manufacturers also have 'load vs inflation pressure' tables for all tires.

This gives the recommended 'cold' pressures for different loads on the same tire.

 

The load/inflation sticker on the door gives the value from that table for the vehicle -- if it has the same size and load rating as it was born with.