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Look, another tire pressure thread!

jsalbre

jsalbre

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I know we've done a million of these, but I need some sanity checking.

I've just installed a set 35x12.5R17 Falken Wildpeak AT4w. Falken's tire pressure chart (https://www.falkentire.com/load-inflation) shows this for this size:

1745516555109.png

I'm sitting at right about 4500 (2250 per tire) pounds on the front axle and 3500 (1750 per tire) on the rear. Based on that chart I'd be good at 32 psi front and under 25 rear (but I'd never go below the chart). I set it to 35 front and 30 rear to give some wiggle room, and it feels just fine, but mentally that just seems too low and looks really squishy. I know I can do the chalk test, and I might, but I would think the tire manufacturer knows the proper pressures for their tires.

Thoughts?
 
I know exactly what you mean by the "mentally it just doesn't seem right" thing, I feel the same way. I don't care what those tire charts say- I do NOT like the feel of underinflated tires. I prefer the firmer feel (not like rolling on caveman wheels but definitely firmer). The "squishy" feel is not for me, even if it might be ok according to the charts and might absorb some of the sharp bumps better. Its a 1-ton pickup truck for cryin' out loud, not a Buick.
 
Just remember, the chart shows the minimum pressure for a given load…no harm in upping the pressure to your liking for ride, handling, or sanity! The pressures listed have nothing to do with tire wear as rim width comes into play so use the number listed as your minimum safe pressure and adjust up to your liking.
 
jsalbre said:
I know we've done a million of these, but I need some sanity checking.

I've just installed a set 35x12.5R17 Falken Wildpeak AT4w. Falken's tire pressure chart (https://www.falkentire.com/load-inflation) shows this for this size:

View attachment 85035

I'm sitting at right about 4500 (2250 per tire) pounds on the front axle and 3500 (1750 per tire) on the rear. Based on that chart I'd be good at 32 psi front and under 25 rear (but I'd never go below the chart). I set it to 35 front and 30 rear to give some wiggle room, and it feels just fine, but mentally that just seems too low and looks really squishy. I know I can do the chalk test, and I might, but I would think the tire manufacturer knows the proper pressures for their tires.

Thoughts?
Click to expand...

35/25 is plenty, and probably rides great with excellent traction. Larger tires don’t need as much air. I run the 285/70R17’s on my TJ at ~14 winter and 18-20 summer, no issues at all.

I’d likely bump the pressures to 40/35 for high speed travel, as long as they wore evenly.
 
I've been running basically 35/30 on all of the different 35x12.50R17 that I have run. Seems to be about the best all around pressure when empty.
If you watch your pressure gage, it will go up about 5 PSI once the tires are up to temp.
 
You’re all pretty much saying what I expected. 35/30 feels right so I’ll stick with that for now and keep a close eye on wear patterns. I’ll of course bump it up when towing.
 
Don’t overthink it my old jeep on 40s I ran 8 PSI it was a perfect wear pattern and plenty of load rating for the weight of it. I bet if you chalk test it you are just about perfect I am running 44F/35R on my truck and its perfect feels great and flat wear
 
Grateful Dad said:
Just remember, the chart shows the minimum pressure for a given load…no harm in upping the pressure to your liking for ride, handling, or sanity! The pressures listed have nothing to do with tire wear as rim width comes into play so use the number listed as your minimum safe pressure and adjust up to your liking.
Click to expand...
Thats completely wrong tire pressure has everything to do with the wear of the tread. Wheel width will change the pressure required to some extent but the pressure is what changes your tread contact with the road.
 
Anyone know what the minimum pressure may be before the TPMS gives an alert? I have 35 12.5 / 20 Toyo, but run 50 all around unless pulling the RV.
 
Sponge60 said:
Anyone know what the minimum pressure may be before the TPMS gives an alert? I have 35 12.5 / 20 Toyo, but run 50 all around unless pulling the RV.
Click to expand...
35 I think but you have a 3500 which does not have TPMS you have TPIS which does not alert for low tires you only shows the pressures on the EVIC
 
H3LZSN1P3R said:
Thats completely wrong tire pressure has everything to do with the wear of the tread. Wheel width will change the pressure required to some extent but the pressure is what changes your tread contact with the road.
Click to expand...
Ok Johnny Ringo, I’ll be your huckleberry…..

Completely wrong?! Did you actually read the post? Everything stated is fact, not opinion. You are correct, tire pressure does indeed have everything to do with tire wear, what I stated was the tire pressure listed in the chart (load inflation table) is specific to the minimum pressure required to safely support a given weight. That’s a safety aspect so you’re not running under inflated which causes heat to build and ultimately lead to tire failure. The standards set in that table are for that purpose, not tire wear. There are multiple things that impact tire wear, but thats not the purpose of the load inflation tables.

A perfect example of this is my wife’s Bronco. It has 315/70/17 in load range c which reach the max load capacity @ 35 psi. However, on this particular tire it’s stamped right on the sidewall that you can actually inflate to a max of 39 psi and guess what Ford has listed on the door jamb? You guessed it, 39 psi. The tire’s weight carry capacity does not increase past 35 psi……the added pressure is for ride and handling characteristics.
 
Grateful Dad said:
Ok Johnny Ringo, I’ll be your huckleberry…..

Completely wrong?! Did you actually read the post? Everything stated is fact, not opinion. You are correct, tire pressure does indeed have everything to do with tire wear, what I stated was the tire pressure listed in the chart (load inflation table) is specific to the minimum pressure required to safely support a given weight. That’s a safety aspect so you’re not running under inflated which causes heat to build and ultimately lead to tire failure. The standards set in that table are for that purpose, not tire wear. There are multiple things that impact tire wear, but thats not the purpose of the load inflation tables.

A perfect example of this is my wife’s Bronco. It has 315/70/17 in load range c which reach the max load capacity @ 35 psi. However, on this particular tire it’s stamped right on the sidewall that you can actually inflate to a max of 39 psi and guess what Ford has listed on the door jamb? You guessed it, 39 psi. The tire’s weight carry capacity does not increase past 35 psi……the added pressure is for ride and handling characteristics.
Click to expand...
The minimums in that chart is for proper inflation at the given weight it will wear equal across the tread at that pressure and weight thats also part of the weight handling….the heat buildup from under inflating is due to the surface contact patch being too small.
 
H3LZSN1P3R said:
The minimums in that chart is for proper inflation at the given weight it will wear equal across the tread at that pressure and weight thats also part of the weight handling….the heat buildup from under inflating is due to the surface contact patch being too small.
Click to expand...
I agree with 99% of what you just said however the minimum in that chart is for load carrying, not tire wear. The table doesn’t take into consideration rim width which will 100% affect the contact patch of the tire. And as you deftly explained above, how that tire supports the weight across the contact patch of the tread will affect the wear.

Take 3 identical Ram HD’s and run the same size LT 285/60/20 Trashforseces. Truck 1 has the factory 20x8’s, truck 2 runs 20x9’s, and truck 3 20x10’s. Inflate them all to the same pressure, let’s say 45 psi. Each one of those trucks will ride and handle different and you can bet the tire wear will be different for all 3. They’ll all be running the correct pressure as stated in the table but they will not all wear the same.
 
H3LZSN1P3R said:
The minimums in that chart is for proper inflation at the given weight it will wear equal across the tread at that pressure and weight thats also part of the weight handling….the heat buildup from under inflating is due to the surface contact patch being too small.
Click to expand...

Ok, now that's just crazy talk.

Disregard that sidewall flex...
 
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