Pressure You Run In Your Tires?

[Bostonian1976]

What do you guys run on your 15" wheels? I have smallish tires - don't know exact size at the moment. I have 30 in there now but the ride is sort of "wandering" lately and I'm wondering if it's the air pressure

[Bostonian1976]

I love begging for replies :)

[Terrys]

I Thought all series trucks wandered ?
I think 30 psi is on the high end of ok, and high pressures may cause a truck to steer funky, but it largely depends on tread type and width. I personally run about 26 psi in my 2A, with quite skinny (7.00x16") Sometimes, a pound or two either way will make the difference.

[Bostonian1976]

I Thought all series trucks wandered ?
I think 30 psi is on the high end of ok, and high pressures may cause a truck to steer funky, but it largely depends on tread type and width. I personally run about 26 psi in my 2A, with quite skinny (7.00x16") Sometimes, a pound or two either way will make the difference.

hmm okay thanks...guess I'll have to play around with it some more....

thanks for replying :)

[Momo]

I've actually run mine as high as 75 psi. Steers easier at low speeds and feels better on the freeway. Downside is a tooth-rattling ride.

Been running 45 psi for awhile now. Best of all worlds.

This is on 235/85 16s on a 109 pickup

[Jim-ME]

I run 42 psi in 33-9.50-15. I don't seem to get heavy wear in the center of the tires which would tell me they are over inflated.

[Bostonian1976]

thanks guys. How straight do you track down the road? I'm really finding that I'm wandering quite a bit lately - I've been driving a BMW Z4 when I'm not driving the Rover though and I'm wondering if it's just the contrast that I'm forgetting about.....

[Tim Smith]

thanks guys. How straight do you track down the road? I'm really finding that I'm wandering quite a bit lately - I've been driving a BMW Z4 when I'm not driving the Rover though and I'm wondering if it's just the contrast that I'm forgetting about.....

I think it's hard to say about the wandering... Are your roads crested? Big hump in the middle with a drop off on each side? My back roads are and it makes the truck want to fall off the side of the road. My car however has power steering and it doesn't seem as effected by the road conditions.

Could that be the effect?

[Bostonian1976]

I think it's hard to say about the wandering... Are your roads crested? Big hump in the middle with a drop off on each side? My back roads are and it makes the truck want to fall off the side of the road. My car however has power steering and it doesn't seem as effected by the road conditions.

Could that be the effect?


Maybe! Yeah they are crested...but it seems to be doing this all the time...on every road. I seem to remember it tracking pretty straight, but now I find that I'm always correcting the steering....and I don't remember doing that last summer....

[Tim Smith]

Maybe! Yeah they are crested...but it seems to be doing this all the time...on every road. I seem to remember it tracking pretty straight, but now I find that I'm always correcting the steering....and I don't remember doing that last summer....

I don't know. It's kind of a guess.

Maybe now is a good time to grease on your steering linkages and oil your swivel balls. It's always a good time to add oil to your rover! :thumb-up:

[Bostonian1976]

I don't know. It's kind of a guess.

Maybe now is a good time to grease on your steering linkages and oil your swivel balls. It's always a good time to add oil to your rover! :thumb-up:

yeah the puddles in my storage unit tell me it's probably time :)

I guess I'll just play with air pressure and see what results I get. Sounds like some of you are saying that 30 is a little low......which always leads to more wandering (softer sidewalls)

[Tim Smith]

...and I don't remember doing that last summer...

Oh. Just reread your post. Now I get it.

It's been a while since you last drove the thing so you've lost your upper body "series strength"! LOL.

There is a good reason why series drivers never get caught up in Bar fights. We tend to look like Popeye!
:p

[Bostonian1976]

Oh. Just reread your post. Now I get it.

It's been a while since you last drove the thing so you've lost your upper body "series strength"! LOL.

There is a good reason why series drivers never get caught up in Bar fights. We tend to look like Popeye!
:p

haha.

I feel like I'm doing the thing like they do in old movies - you know when they spend about 5 minutes looking at the person that they're talking to next to them while moving the wheel back and forth a lot on a straight road? (and the fake scenery whizzes by?)

Checked all linkages and components - everything is good and tight. Steering column is well screwed down to the frame (when I first bought it, these nuts were pretty loose and the steering had a lot of slack)

[Tim Smith]

yeah the puddles in my storage unit tell me it's probably time :)

I guess I'll just play with air pressure and see what results I get. Sounds like some of you are saying that 30 is a little low......which always leads to more wandering (softer sidewalls)

FWIW, I run 25psi all around in my tires which are 33" mud terrains mounted on 16" wheels. Not only have they calmed the ride a bit, I think they have helped the grip.

About 6 months ago I was running closer to 40 psi and was complaining that the thing was locking up the brakes too easily in emergency stops. Lowering the pressure seems to have helped with these mud tires.

Cheers,

[daveb]

hey guys

my land rovers have all tracked dead straight when properly setup, I can let go of the steering wheel for a good while. no BS.

something is wrong if you can't.

I run radials anywhere from 32-40psi. i think the factory recommendation was for 28-32 with bias plys, those tend to have thicker sidewalls though so you generally want to go higher with a radial which tend to have thinner sidewalls.

35-36 should work for most conditions. back before I knew what I was doing I ran a friend's 109 up to maine for the downeeast rally, the guys on the trail were dumbfounded when I told them I was running 80psi. no wonder I couldn't get over the smallest obstacle. the truck really came alive when we aired down to 25...
:thumb-up:

btw I didn't put all that air in there. I won't say who did though he knows who he is. but I didn't think anything was wrong with it so I'm just as guilty.

the guy who said he is running 75 psi, those tirs are going to be bald in the middle before long, it is too high for a series LR even heavily loaded.

rgrds
dave

[jp-]

32-35 in the front.

30-38 in the rear, depending on load conditions.

Bias ply.

[Momo]

the guy who said he is running 75 psi, those tires are going to be bald in the middle before long, it is too high for a series LR even heavily loaded.

That was me Dave- and I gotta call BS on that. My tires are ten years old with 30k miles.

http://s194.photobucket.com/albums/z251/Momo109/?action=view&current=P5290035.jpg

[msggunny]

Read this in a 4X4 mag and tried it myself. Take kidies sidewalk chalk and mark your tires from edge to edge in 2 different places, 90deg and 45 or similar. Drive in a straight line, 50-100 ft, with your tires at normal operating temprature and then check the tires. if the chalk is worn only in the middle then you have too much air. Worn on the sides only, not enough. The chalk should be worn evenly across, air up or down until you get there.

Hope it helps and i didnt confuse anyone.

[Jim-ME]

My Rover doesn't seem to wander at all and also tracks straight. Maybe your toe-in adjustment needs to be checked. Are your tires wearing evenly?

[daveb]

hey momo, I'm just trying to be helpful. not sure what you think you are gaining by running two times the manufacturer's pressure. But from looking @ your photograph it appears the outer tread blocks are twice as deep as the inner rows.

best,
Dave


That was me Dave- and I gotta call BS on that. My tires are ten years old with 30k miles.

http://s194.photobucket.com/albums/z251/Momo109/?action=view&current=P5290035.jpg

[PH4]

I have an issue especially arounr 35-40 mph with the steering wheel shuddering back and forth. A little unerving. Could this be from incorrect tire pressure? Seems better under acceleration and worse when not under throttle? Any thoughts?

[Momo]

hey momo, I'm just trying to be helpful. not sure what you think you are gaining by running two times the manufacturer's pressure. But from looking @ your photograph it appears the outer tread blocks are twice as deep as the inner rows.


No worries Dave, as they say "your mileage may vary". Actually the lighting in the photo may be misleading- the tread is a bit more worn on the outside due to normal cornering etc. but otherwise they are evenly worn.

Mfr. pressure is max 80 psi cold. Only reason I ran them @ 75 was all the freeway driving I used to do, it cut down on rolling resistance. Oh, and parking lot maneuvers! Definitely makes a difference but like I say you pay for it in ride quality- if a Series truck can even have such a thing.

Gunny, I like the chalk trick. I'll have to wrestle my kid for it though.

[daveb]

yes, my mileage will vary. you may get more MPG but god help you if you hit any kind of surface that offers less than optimal traction. Please, do not advocate this dangerous practice to others. Momo, look on the side of the tire. There you will see where the manufacturer has spelled out for you the maximum pressure for the tire along with a figure in kilograms and/or lbs. If the vehicle is not putting that much weight on THAT tire, then the tire is overinflated. You can protest all you want but it is simply not correct. Yes it is a "free country" but you are endangering yourself and your passengers as well as the occupants of other vehicles. Sorry mate.



No worries Dave, as they say "your mileage may vary". Actually the lighting in the photo may be misleading- the tread is a bit more worn on the outside due to normal cornering etc. but otherwise they are evenly worn.

Mfr. pressure is max 80 psi cold. Only reason I ran them @ 75 was all the freeway driving I used to do, it cut down on rolling resistance. Oh, and parking lot maneuvers! Definitely makes a difference but like I say you pay for it in ride quality- if a Series truck can even have such a thing.

Gunny, I like the chalk trick. I'll have to wrestle my kid for it though.

[Bostonian1976]

sounds like I'm underinflated at 30 psi. Here's what I'm running. I can't make out the size though lol. (the truck is an hour away so I can't go look at it). By the way this is the leakiest hub I have of all 4...

[daveb]

if it is the kind of shuddering where the wheel is about to be wrenched from your hands, try getting the wheels balanced. additionally you may need to rebuild or replace the steering relay through the frame and/or adjust or replace the steering kingpins, busihngs, and bearings in the swivel housing.

good luck, that is not a fun sensation.


I have an issue especially arounr 35-40 mph with the steering wheel shuddering back and forth. A little unerving. Could this be from incorrect tire pressure? Seems better under acceleration and worse when not under throttle? Any thoughts?

[daveb]

bostonian you are probably fine, I like em a bit higher though one or two do tend to leak, then hold @ around 20ish. I guess I should run tubes. now that i've scolded momo for endangering others I guess I should follow the same practice...

that wheel looks like most I've seen. that kind of leakage is quite common. you may want to check the axle breather though b4 it gets too much worse.


sounds like I'm underinflated at 30 psi. Here's what I'm running. I can't make out the size though lol. (the truck is an hour away so I can't go look at it). By the way this is the leakiest hub I have of all 4...

[jp-]

yes, my mileage will vary. you may get more MPG but god help you if you hit any kind of surface that offers less than optimal traction. Please, do not advocate this dangerous practice to others. Momo, look on the side of the tire. There you will see where the manufacturer has spelled out for you the maximum pressure for the tire along with a figure in kilograms and/or lbs. If the vehicle is not putting that much weight on THAT tire, then the tire is overinflated. You can protest all you want but it is simply not correct. Yes it is a "free country" but you are endangering yourself and your passengers as well as the occupants of other vehicles. Sorry mate.

I have to agree with DaveB here. 75psi is waaaaay too much for normal driving. If you try stopping on a slick surface you are going to slide a whole lot sooner at 75psi than at 35psi. The 80psi marking on the tire is a maximum inflation pressure NOT a recommended tire pressure. In other words, if you are going to be hauling a load at or near the tires maximum weight carrying rate, then (and only then) will you need the tire inflated to (or close to) the maximum inflation rating.

It's not rocket science. And just because your tires don't seem to be wearing overly in the center, doesn't mean that you have them at the right pressure. All it means is that the tire may have a stiffer carcass than another tire, which would show wear in the center at the same psi.

You are sacrificing ride quality (such as it is in a Land Rover) and safety (yours and others) at the expense of tire life. Not a worthwhile trade.


Flame off.

[Momo]

Read my original post again, guys. You are taking this way too seriously.:)


"I've actually run mine as high as 75 psi. Steers easier at low speeds and feels better on the freeway. Downside is a tooth-rattling ride. Been running 45 psi for awhile now. Best of all worlds."

Later Dave said:


Please, do not advocate this dangerous practice to others.

I never advocated any given pressure. I just thought I was answering an informal poll! I never said 75 was not high, and I never said it was a recommended pressure.

Dave's bent because he didn't like my response to his assertion about my tires wearing prematurely. Not tires in general, but my tires. Over that period I ran at high pressure, I watched for increased wear, and it didn't happen.

Maybe I should have been more conciliatory in my approach, but I was using the expression "calling BS" in a tongue in cheek way which obviously went over like a lead balloon. Dave has recieved a private apology for that misstep and I will say it here too, Dave, that I'm sorry I irked you.

But...in fairness to logic, for you to claim that running high pressure amounts to endangering others? In general, that is just ludicrous and here's why:

Over the year period in 2002 when I ran high pressure, I clocked about 8k commuter miles, and on and off for about 1100-1800 fwy miles for long distance trips. Many of those miles were with a cargo load. Always in good weather. Most of those miles were at between 45 and 60 mph and wouldn't be considered pushing the performance envelope by any stretch. We are talking about a Land Rover after all- slow lane, the whole world passing you at 80 mph, et cetera.

Would I run that pressure in the rain, snow, on loose surfaces, or other poor conditions? Of course not. I have the benefit of about 330 days of sunshine per year and two vehicles. JP's point about slick roads is well taken...but a rarity in my neck of the woods. On crappy days the 109 stayed home.

Furthermore, in numerous industry and govt. tests, radial tires have been hydraulically pressurized up to 300 psi prior to failure. Most tire failures were at the bead and in fact many failures during testing were rim structural failures, not tire failures. Radial tires are one of the most technologically advanced items in the automotive industry and their tolerances are well established. If anything underinflation is by far the greatest danger.

Finally, today I called a Firestone retailer to get their take and as expected he agreed that 75 is too high for routine use in all conditions, but he actually laughed when he heard your safety argument and felt it was overstated. His main concern was ride quality and the possibility of premature wear.

Group hug everyone...:D

[jp-]

Well, I'm still pissed.

-kidding.

Actually everything depends upon the load on the tire as to what the "correct" psi is. 75psi would be probably be ok if all you do is haul bricks around in your loadbed. However, since most people don't do this, 75 is considered high. Also, the psi would not be the same for front and rear tires even if hauling bricks. The rear tires are going to take a disproportionate amount of the weight and therefore will need to be higher than the fronts.

If you had said something like, "I run 35psi in the front, and 45psi in the back due to the amount of hauling that I do," nobody would have said a thing.

Are you endangering others, well we may have been a little judgmental here. However, no one knows you as a driver and most drivers are going to be considerably less safe when they are not prepared for the handling affects caused by overinflated tires (or any other condition they are not used to). You said that you never drive in wet weather, so therefore we can surmise that you don't know how your tires are going to respond in wet conditions at 75psi. If you get caught in a downpour, (which happened to me 3 weeks ago) you are now endangering others, because you don't know how the handling of your vehicle will be affected. Is it a long shot? Maybe, but maybe not.

See the point? Or did I over analyze?

[daveb]

Read my original post again, guys. You are taking this way too seriously.:)


you are right. we are. apology accepted. I know you live in sunny CA where rain and ice never happen, and was going to mention that. I just want to make sure that the people reading this list who may not know any better understand that it is *not* a good idea to run twice the vehicle manufacturer's suggested tire pressure.

to encapsulate the point, nobody is saying that your truck is going to randomly fly off the road *right now* because of the tire pressure. but at 75 psi your contact patch is reduced and no amount of protest on your part or anyone else's will change the fact that traction is then reduced as well, regardless of the surface.

rgrds
dave

[Momo]

See the point? Or did I over analyze?

I agree 100% JP & Dave, which is why I qualified things in my last post. I'm well aware of the potential for traction loss/reduced brake effectiveness on slick surfaces (I drive large vehicles in all weather conditions year round) and my level of care doesn't change when I'm in my personal vehicle. So I think we are on the same page here.

I think we win the award for thread hijack this week...