Hemi Idle hours

[AH64ID]

Thanks for sending this! A quick scan of this document indicates I should be running at 55 psi with my tires (315/70 R17 Load Range E), since the lower psi seems to be for different tires. But that was just based on skimming the document; I will spend more time reading through it later.

Ahh... that's a slightly different tire size than you originally indicated.

A 315/70R17 LRE holds the same weight at 50, 55, 60, and 65 psi thanks to a TRA limitation on 17's to 3195lbs. When you read the chart the C, D, and E under pressures indicate the max pressure for that load range. I.E. all 3 load ranges can support the same weight at 35 psi, but only LRD and LRE can run more than 35 psi and support more weight.

 

[stickshifter]

Ahh... that's a slightly different tire size than you originally indicated.

A 315/70R17 LRE holds the same weight at 50, 55, 60, and 65 psi thanks to a TRA limitation on 17's to 3195lbs. When you read the chart the C, D, and E under pressures indicate the max pressure for that load range. I.E. all 3 load ranges can support the same weight at 35 psi, but only LRD and LRE can run more than 35 psi and support more weight.

Perhaps I originally said I was running 35s? Sorry - I usually refer to 315/70 R17 as a "35" even though its a metric. Thanks for the extra info!

 

[Rockcrawlindude]

I'm inflating to factory specs: 60 psi for the front tires, 65 for the rear (if I don't have weight in the bed, I just go to 60 in the rear).

Here is my door sticker:

View attachment 90379

The specs for my tires are a max inflation of 65 psi (cold).

Are most folks running a lower psi? If so, about what psi? Last question: how are folks judging what psi is okay to run if the factory spec is 60/65?

I'm coming from Jeep Wranglers and Toyota Tacomas, so the world of HD trucks is new to me, as are these high psi factory specs.

I run ~ 45 psi Plenty of load capacity and better ride. Depending on your load range you can probably run a lot lower and be golden.

 

[AH64ID]

I run ~ 45 psi Plenty of load capacity and better ride. Depending on your load range you can probably run a lot lower and be golden.

I run 40/35 empty on my Hemi, plenty of capacity and a great ride/traction.

 

[Rockcrawlindude]

I run 40/35 empty on my Hemi, plenty of capacity and a great ride/traction.

I could run a little lower but I’m a little heavy for a Hemi and I also have a sprinkle of the ‘tism so it makes my little brain happier to have the fronts and rears the same psi.

45 for me is the line between good enough ride and not needing to air up when I hook up the trailer

 

[stickshifter]

@Rockcrawlindude and @AH64ID - thanks for your information. I'm definitely going to air-down a bit.

Rockcrawlindude - looks like you are running 285/75 R18 tires. So that's roughly a 33" tire on 18-inch wheels [EDIT: my bad, this measures out to around 35" in diameter]. What tire are you running, and what is the load range for your tires?

AH64ID - are you running the factory GY Duratracs? Those are 285/70 R17, but I can't remember if the factory tires are Load Range D or E; do you know the Load Range on your tires?

Thanks!

 

[Rockcrawlindude]

@Rockcrawlindude and @AH64ID - thanks for your information. I'm definitely going to air-down a bit.

Rockcrawlindude - looks like you are running 285/75 R18 tires. So that's roughly a 33" tire on 18-inch wheels. What tire are you running, and what is the load range for your tires?

AH64ID - are you running the factory GY Duratracs? Those are 285/70 R17, but I can't remember if the factory tires are Load Range D or E; do you know the Load Range on your tires?

Thanks!

285/75-18 about 35” OD
Duratracs
Rated 4080@80psi

 

[AH64ID]

@Rockcrawlindude and @AH64ID - thanks for your information. I'm definitely going to air-down a bit.

Rockcrawlindude - looks like you are running 285/75 R18 tires. So that's roughly a 33" tire on 18-inch wheels. What tire are you running, and what is the load range for your tires?

AH64ID - are you running the factory GY Duratracs? Those are 285/70 R17, but I can't remember if the factory tires are Load Range D or E; do you know the Load Range on your tires?

Thanks!

Mine isn't a PW.

275/70R18 Cooper ST Maxx's (for now, switching to Duratrac RT-LT's in the same size when I decide to pull the trigger). 3640@80psi.

 

[stickshifter]

@Rockcrawlindude @AH64ID - thanks gentlemen!

 

[ramblinChet]

My truck hit 100,000 miles on the trail, and the stats look solid: 14.3% idle (476/3,334 hours) and 85.7% drive time (2,858/3,334 hours). My total engine hours are about average for 100,000 miles, with lower-than-typical idle time and higher drive time. The moving average of 35 mph (100,000 miles/2,858 hours) impressed me, aligning perfectly with my mixed trail (15–20 mph) and backroad (50–55 mph) driving habits.

 

[matemike]

2022 original owner for exactly 3 years and 4 months now.
55555 total miles today
Idle 169
Drive 1169
Total 1338
12.63% idle time. I get stopped at a lot of train tracks.







And yes, I do truck stuff …

 

[matemike]

This thread makes me wish there was a dot mark or check box on the hour meter that is currently counting the seconds, minutes, HOURS.
As in, put an indicator on either the idle hour number or drive hour number; whichever is counting at that time.
Because I have the same question: when is idle counting? ...in park only? while stopped at a light? while idling but moving with no throttle (example: through a parking lot)? any time going less than 5 mph? or 10 mph?

 

[Rockcrawlindude]

This thread makes me wish there was a dot mark or check box on the hour meter that is currently counting the seconds, minutes, HOURS.
As in, put an indicator on either the idle hour number or drive hour number; whichever is counting at that time.
Because I have the same question: when is idle counting? ...in park only? while stopped at a light? while idling but moving with no throttle (example: through a parking lot)? any time going less than 5 mph? or 10 mph?

Don’t know about stopped at a light, but moving would certainly be drive time.

 

[dieselscout80]

This thread makes me wish there was a dot mark or check box on the hour meter that is currently counting the seconds, minutes, HOURS.
As in, put an indicator on either the idle hour number or drive hour number; whichever is counting at that time.
Because I have the same question: when is idle counting? ...in park only? while stopped at a light? while idling but moving with no throttle (example: through a parking lot)? any time going less than 5 mph? or 10 mph?

That’s a cool idea to show what mode you are in.