BajaNomad

Correct tire psi for highway and bumpy road

Lee - 1-22-2020 at 10:15 AM

My Toyota Highlander has tires rated for 31 psi. I live couple miles down a very rutted and dusty road. Is there an ideal psi for both types of driving?

I'm not looking to air up and down. Just one pressure for both.

mtgoat666 - 1-22-2020 at 10:25 AM

under-inflated tire are unsafe for highway speeds (they roll off rim in hard turns in emergency situation, such as swerving to avoid road hazard).
so best to keep inflated for highway driving, follow door placard pressure recommendation for stock tire, or follow load tables for non-stock tires.
yes, washboard is more comfortable with lower air pressure...

one solution is get your neighbors to chip in some $$ and blade your road periodically :light:

Mr. Bills - 1-22-2020 at 11:19 AM

1. Get your vehicle weighed (or make the most educated guess you can based on published curb weight and the weight of the gear, tools, etc. you carry).

2. Look up your tire size and load rating in the Rim and Wheel Association Load Inflation Tables, which are reprinted by Toyo here:

https://www.toyotires.com/media/2125/application_of_load_inf...

That will give you the air pressure necessary to carry the actual load on each tire, which will be the minimum pressure you should run if you don't have a means to air up.

You will probably find that the tire pressure rating in the vehicle door includes a safety factor of at least 2X when compared to air pressure values in the tables for the actual load on each tire.

Google says that the typical late model Toyota Highlander comes equipped with P245/60R18 tires and that its curb weight is 4,165-4,665 lbs. Adding an allowance for people and stuff would probably bring it to a fully loaded weight of 5,000-5,400 lbs., which would be 1,350 lbs. per tire. Applying the values in the load inflation table (and dividing by 1.1 as suggested in the table notes for using P rated tires on a light truck or heavy SUV) would suggest that you can run 26 psi both on and off road without any problems. (The table shows 26 psi for 1,731 lbs and 1731/1.1=1,573 compared to your theoretial actual load of 1,350.) If you are comfortable extrapolating minimum air pressures for 1,350 lbs you could probably run 22-24 psi as an all purpose pressure.

For a real world comparison, I typically air down LT265/75R16-E tires on a 5,000 lb. vehicle to 16-18 psi for washboard roads and 12 or so for trails. For sand I usually try 10 psi and adjust as necessary. (On washboard, the ride doesn't become noticeably better until I am below 24 psi.) I air up with a Viair 400 series compressor. The sidewalls on your tires are shorter and more compliant (if you use stock tires) so your air pressures would not be as low.

David K - 1-22-2020 at 11:51 AM

Mr. Bills, that is very impressive! So good, in fact, I removed my shorter reply!

basautter - 1-22-2020 at 01:44 PM

I agree with Mr. Bill and David K. Get deflators and a good compressor. I have a ViAir compressor that I am happy with, but there are other good options. You will save time, be more comfortable with less wear on your truck off road, and be safer on pavement.

JZ - 1-22-2020 at 01:47 PM

Run Load E tires on my 3/4 ton:

60-65 - highway

35 - dirt roads

25 - sand

15 - getting out of very deep sand



Udo - 1-22-2020 at 02:01 PM

I totally agree with bills explanation. Living in BAJA has really made me aware of tire pressures in a variety of terrains. My wife and I have been 4-wheeling so long that I now just use my gut instinct by looking at the sidewalls of the tires (both the FJ Cruiser and the RZR turbo 4 seater). I only use the tire gauge just to confirm what pressure I am running.


Quote: Originally posted by David K  
Mr. Bills, that is very impressive! So good, in fact, I removed my shorter reply!

Marc - 1-22-2020 at 06:02 PM

Quote: Originally posted by Mr. Bills  
1. Get your vehicle weighed (or make the most educated guess you can based on published curb weight and the weight of the gear, tools, etc. you carry).

2. Look up your tire size and load rating in the Rim and Wheel Association Load Inflation Tables, which are reprinted by Toyo here:

https://www.toyotires.com/media/2125/application_of_load_inf...

That will give you the air pressure necessary to carry the actual load on each tire, which will be the minimum pressure you should run if you don't have a means to air up.

You will probably find that the tire pressure rating in the vehicle door includes a safety factor of at least 2X when compared to air pressure values in the tables for the actual load on each tire.

Google says that the typical late model Toyota Highlander comes equipped with P245/60R18 tires and that its curb weight is 4,165-4,665 lbs. Adding an allowance for people and stuff would probably bring it to a fully loaded weight of 5,000-5,400 lbs., which would be 1,350 lbs. per tire. Applying the values in the load inflation table (and dividing by 1.1 as suggested in the table notes for using P rated tires on a light truck or heavy SUV) would suggest that you can run 26 psi both on and off road without any problems. (The table shows 26 psi for 1,731 lbs and 1731/1.1=1,573 compared to your theoretial actual load of 1,350.) If you are comfortable extrapolating minimum air pressures for 1,350 lbs you could probably run 22-24 psi as an all purpose pressure.

For a real world comparison, I typically air down LT265/75R16-E tires on a 5,000 lb. vehicle to 16-18 psi for washboard roads and 12 or so for trails. For sand I usually try 10 psi and adjust as necessary. (On washboard, the ride doesn't become noticeably better until I am below 24 psi.) I air up with a Viair 400 series compressor. The sidewalls on your tires are shorter and more compliant (if you use stock tires) so your air pressures would not be as low.


Huh?

David K - 1-22-2020 at 06:36 PM

Quote: Originally posted by Marc  
Quote: Originally posted by Mr. Bills  
1. Get your vehicle weighed (or make the most educated guess you can based on published curb weight and the weight of the gear, tools, etc. you carry).

2. Look up your tire size and load rating in the Rim and Wheel Association Load Inflation Tables, which are reprinted by Toyo here:

https://www.toyotires.com/media/2125/application_of_load_inf...

That will give you the air pressure necessary to carry the actual load on each tire, which will be the minimum pressure you should run if you don't have a means to air up.

You will probably find that the tire pressure rating in the vehicle door includes a safety factor of at least 2X when compared to air pressure values in the tables for the actual load on each tire.

Google says that the typical late model Toyota Highlander comes equipped with P245/60R18 tires and that its curb weight is 4,165-4,665 lbs. Adding an allowance for people and stuff would probably bring it to a fully loaded weight of 5,000-5,400 lbs., which would be 1,350 lbs. per tire. Applying the values in the load inflation table (and dividing by 1.1 as suggested in the table notes for using P rated tires on a light truck or heavy SUV) would suggest that you can run 26 psi both on and off road without any problems. (The table shows 26 psi for 1,731 lbs and 1731/1.1=1,573 compared to your theoretial actual load of 1,350.) If you are comfortable extrapolating minimum air pressures for 1,350 lbs you could probably run 22-24 psi as an all purpose pressure.

For a real world comparison, I typically air down LT265/75R16-E tires on a 5,000 lb. vehicle to 16-18 psi for washboard roads and 12 or so for trails. For sand I usually try 10 psi and adjust as necessary. (On washboard, the ride doesn't become noticeably better until I am below 24 psi.) I air up with a Viair 400 series compressor. The sidewalls on your tires are shorter and more compliant (if you use stock tires) so your air pressures would not be as low.


Huh?


The short answer is 26 psi! :lol:

Lee - 1-22-2020 at 09:26 PM

Quote: Originally posted by Mr. Bills  
1. Get your vehicle weighed (or make the most educated guess you can based on published curb weight and the weight of the gear, tools, etc. you carry).

2. Look up your tire size and load rating in the Rim and Wheel Association Load Inflation Tables, which are reprinted by Toyo here:

https://www.toyotires.com/media/2125/application_of_load_inf...

That will give you the air pressure necessary to carry the actual load on each tire, which will be the minimum pressure you should run if you don't have a means to air up.

You will probably find that the tire pressure rating in the vehicle door includes a safety factor of at least 2X when compared to air pressure values in the tables for the actual load on each tire.

Google says that the typical late model Toyota Highlander comes equipped with P245/60R18 tires and that its curb weight is 4,165-4,665 lbs. Adding an allowance for people and stuff would probably bring it to a fully loaded weight of 5,000-5,400 lbs., which would be 1,350 lbs. per tire. Applying the values in the load inflation table (and dividing by 1.1 as suggested in the table notes for using P rated tires on a light truck or heavy SUV) would suggest that you can run 26 psi both on and off road without any problems. (The table shows 26 psi for 1,731 lbs and 1731/1.1=1,573 compared to your theoretial actual load of 1,350.) If you are comfortable extrapolating minimum air pressures for 1,350 lbs you could probably run 22-24 psi as an all purpose pressure.

For a real world comparison, I typically air down LT265/75R16-E tires on a 5,000 lb. vehicle to 16-18 psi for washboard roads and 12 or so for trails. For sand I usually try 10 psi and adjust as necessary. (On washboard, the ride doesn't become noticeably better until I am below 24 psi.) I air up with a Viair 400 series compressor. The sidewalls on your tires are shorter and more compliant (if you use stock tires) so your air pressures would not be as low.


Wow thanks for that -- you too DK. A number I came across today in more research was 10% of recommended psi. Which at 31 psi is 3 psi or so. So, 26-28 psi sounds doable.

Mr. Bills - 1-22-2020 at 11:43 PM

Don't be afraid to air down to 26 or even 24. I don't think deflating from 31 to 28 is going to make any real difference on washboard roads.

bajatrailrider - 1-23-2020 at 08:29 AM

Mr bills is correct. As you can never go by door sticker psi. All depends what tires you have.

4x4abc - 1-23-2020 at 09:53 AM

door sticker and manual are guidelines for the average driver
modifying tires and using them on not every day surfaces requires a different approach

to find the "normal" pressure for your non stock tires use the chalk method
normal is the pressure for driving around town on perfect asphalt - short freeway trips included
lets say "normal" turned out to be 30 psi
for long, fast freeway trips add 10 psi - bringing you to 40psi
rough roads, moderate off-road (Baja dirt roads) reduce normal by 1/3 - bringing you to 20 psi (drastically reduces flat tires on dirt roads as well
for mud, sand and snow (Baja beaches) reduce 2/3 from normal - bringing you to 10psi
emergencies (about to be swallowed by the quick sand at Malarrimo) reduce "mud, sand, and snow by 50% - bringing you to 5psi
No you don't need beadlocks for that - just avoid radical steering and tight turns under acceleration

if you don't follow this guideline because you don't feel comfortable with the recommendations, you will not harvest the advantages lower pressures will afford you
airing down just a little bit will not achieve anything

but feel free to play around with those numbers
my normal for example is 29psi, but around town (all very short driving distances) I chose to run my tires at 25psi for more comfort. Emergency braking improves dramatically with lower pressure

David K - 1-23-2020 at 10:19 AM

Here is my detailed Chalk Test post with photos (on Tacoma World forums): https://www.tacomaworld.com/threads/chalk-test-dynapro-atm-a...

The text only:

Step 1, check that your tires are all at the pressure you assunme to be correct.

For my Dynapros, they all are at 37 psi. I have (by feel) determined 36-40 psi to be a good range for these 44 psi max. tires on my lightly loaded to unloaded 4 door Tacoma.

Step 2, with big sidewalk chalk, make a one inch bar across the tread.

Step 3, drive for approx. 100 feet and then see how the chalk wears off.

If it wears mostly in the center, too much air. If more wears on the outsides, then too little air. If wears is even across the tire, you are gold!

...after doing the test, I have lowered the psi to 35 on all 4... soon I will re-test and see if we have improved wear even-ness...

[I made one more adjustment to 34 psi and my tires are lasting "forever", wearing evenly]

Mr. Bills - 1-23-2020 at 10:50 AM

Getting lost in this discussion of how to find the "correct" tire pressure is the fact that there is no single correct pressure and the member who posited the original question doesn't carry an air compressor.

1. The "correct" pressure depends upon the weight of the vehicle, the size and load rating of the tire, and the road or surface conditions, the speed being driven, etc.

2. The "correct" pressure changes as these factors change.

3. Regardless of tire pressure, Baja is very hard on tires, witnessed by the ruined tire carcasses that litter the roadsides. [Ironically, many are within sight of signs reading "No Tire Basura," which lead one of the young teenagers on our recent trip to quip "Why are there always piles of old tires next to signs that say No Tire Trash?" ]

Since there is no single correct tire pressure for all conditions and Baja is hard on tires regardless of tire pressure, one should always carry a good spare, a tire repair kit such as the ones sold by Safety Seal and ARB, a good air gauge and simple deflators, and a compressor of some sort.

One may be lucky and never need all of these items, however luck favors the prepared.

gnukid - 1-23-2020 at 10:57 AM

Also, its important to change tire pressure to even out wear, for those of us who need to air down, we need to air back up for highway trips, its an extra effort but its better to air down and air up more often then leave it aired down. For me big difference at every pressure point, 22, 23, 24, 25, 26 I just decided to reupholster my seats with extra support to save the stress on the body traveling on back roads, and of course new shocks and check the springs and an everything.

4x4abc - 1-23-2020 at 11:36 AM

the chalk test addresses all variances to find "normal" tire pressure
vehicle weight, tire volume of air, load range etc

nobody is asking for a correct pressure
all values recommended are derived from user experience
leaving the perfect world of pavement, traffic lights, warning signs etc drivers are asked to be adaptive, creative to make tires and spine live healthy
all recommendations given can be experimented with

tires only do not need to be aired up from lower off-road pressures when re-entering pavement if you keep your speed below 40mph
that way even people without a compressor can air down for off-road and then later safely drive on pavement (slow) to the next gas station

sidewalk = side wall

No tire basura = Don't throw trash out = Don't litter

David K - 1-23-2020 at 01:59 PM

Harald, maybe consider adding your website link as a signature on Nomad posts. I think your www.4x4abc.com web page is excellent!

There are many many pages of info on your site, and not all are listed on the first page... you need to do some exploring on 4x4abc.com! ;)

Here is one tire pressure page: http://4x4abc.com/jeep101/soft-sand-deflate.html

4x4abc - 1-23-2020 at 09:45 PM

I know - I know, David

I have a few thousand pages out there

here is a good one for Baja beaches:
http://4x4abc.com/jeep101/soft-sand-turn-straight.html

I am slowly putting my life back together (has been almost 3 years since I broke my foot, wheelchair for too long, crutches for too long)
the last year I have been catching up on house repairs/maintenance
catching up on vehicle repairs/maintenance (I have still have 5 - sold 3)
https://www.facebook.com/photo.php?fbid=10158923615347281&am...

re-establishing my guide service and updating my web sites is next

and then there are still a few books I need to finish

ahh - forgot - youtube channel is coming too (Baja, 4WD, driving, surviving)

don't even know what boredom is

4x4abc - 1-23-2020 at 09:47 PM

and no, I will not add my web sites to the signature

I hate credentials
people who need to find me - find me

David K - 1-24-2020 at 09:15 AM

I am very happy for you getting your life back together. You were such a good host to me in August 2017, and that was not long after your injury.

Having your web page links ('signatures') on Nomad with your posts (as I do) are not 'credentials' (to me, anyway). They are helpful tools so that your readers can find out more about Baja or more about four wheeling without searching for answers. www.4x4abc.com is a huge resource to HELP the Baja traveler with 4x4 driving knowledge (and more) in the same way that www.vivabaja.com is designed to help find the locations and history in Baja that people may want to see more of.

bajatrailrider - 1-26-2020 at 08:45 AM

Living in Ca dirt bikes and 4x4. I never aired down like living in Baja. Even pavement here bad as always road construction. Nissan diesel 26 psi off road 16psi 33in tires. Bronco full size dirt only 15 psi 35in tires. Toyota off road go fast truck 16 psi 35 in. Dodge diesel 45 psi off road 20psi 34 in. Yamaha yxz sxs 8 psi will go down to 5 psi . All dirt bikes with cheater tires 6 psi . With desert tire stiff ply knobby 2 psi. Atv 700 2 psi. Have fun guys.