Is this even Possible?

[apes4x4]

Thought I'd bring it up with inquiring minds.

WalMart. Tire and Lube Express.

I took my old truck (chev) and my new truck (taco) in to have the tires swapped this weekend. Things went well. The service: good. The shop guys: good. The price: Fantastic!

When I got my truck home and settled into the garage, I came across alarming inconsistency with the tire pressures . Rear drivers: 34. Front drivers: 37. Rear Pass: 32. and Front Pass: 57!! FIFTY-SEVEN?!?? -Five - Seven

Can that even happen? I think a tire would explode at that point!?
Is there any thing else I should look into myself to makes sure things are kosher?
Sorry for all the question and exclamation marks. Is it just me?

A

[canadian bum]

Walmart is good for mounting tires for cheap but after i get any tire mounted I personally check tire pressures no matter where I get the tires done. And your tires are probably rated for 65psi max so your okay. For Highway set your tires for 25 front and 19 rear. I run mine 26 front and 20 rear and my truck is heavier.

Your chev set your tires for 30psi front and rear since you don't drive it.

[Tarzan]

Just curious why you run lower in the rear tires. Most oem specs are same front rear or higher in the rear for load capacity.

[RiceFarmer]

Walmart is good for mounting tires for cheap but after i get any tire mounted I personally check tire pressures no matter where I get the tires done. And your tires are probably rated for 65psi max so your okay. For Highway set your tires for 25 front and 19 rear. I run mine 26 front and 20 rear and my truck is heavier.

Your chev set your tires for 30psi front and rear since you don't drive it.

25 Psi front? 19 Rear? I strongly don't recommend doing that, especially April I think you still have the factory Rugged Trails which are P metric (thinner sidewall). Set your tires to 32psi all around and you can't go wrong. I set every vehicle to that spec, and for years have NOT had a problem. With that said, your tire pressure light will probably go off depending how sensitive it is, I'm surprised it didn't go off with 57psi! If you have Q's, feel free to PM me.

[apes4x4]

Since we're all on the topic now (and Victor - fyi). The new tires I'm running on my Taco are BFG All-Terrains LT265/75R16's.
When I came across the whack tire pressure settings, I air'd down all my tires to 32. I will for sure be checking my tire pressures after any shop get's ahold of my truck(s) - they always seem to like to change them for me.
Now, I should go check on my Chev which is just sittin' in my parent's driveway so no big deal (for now) but I'm interested to know.

Thanks all.

[Grandpa Smurf]

If your OEM tire is "P" rated and now you run "LT" you need to increase the pressure to carry the same load as you "P" rated tires. With the "Tri-Guard" side walls you need more pressure to keep the tread running flat and maximize your tread life. Stop buy and see me @ Costco Tire south and I will show you the load tables.
Blake (Tire Centre Manager) 313-7655

[apes4x4]

If your OEM tire is "P" rated and now you run "LT" you need to increase the pressure to carry the same load as you "P" rated tires. With the "Tri-Guard" side walls you need more pressure to keep the tread running flat and maximize your tread life. Stop buy and see me @ Costco Tire south and I will show you the load tables.
Blake (Tire Centre Manager) 313-7655

Costco South? Deerfoot Meadows?

The tires I took off my Taco (now on chev): Toyo Open Country A/T's LT265/70 R16's

[Krazie Sj]

Just curious why you run lower in the rear tires. Most oem specs are same front rear or higher in the rear for load capacity.

Cause there's more weight in the front so you want more pressure up there to keep the tires from cupping.



Can that even happen? I think a tire would explode at that point!?

You could probably put over 100psi in that :):):):):):) before it blows out just sitting there.

[freeze]

Yeah you should be fine, just re-inflate them.

I'd echo about John's tire pressure at 25 and 19 should be chalk tested first if you're going that low. The differential is a bit extreme for same width rims.

On a car your dynamics will change as you get more heat into the tire. The rears in John's case will heat up more quickly and it'll change the dynamics on your truck the faster you drive. Front and rear tires shouldn't be more than 2-3 PSI apart if you're running the same width rim front and rear unless you're carrying a bunch of stone or cement etc..

Now if you're rim is wider in the rear then you're PSI is going to be very different as the rear will be higher than the front like 3-6PSI difference. AKA: Having staggered rims (narrow front, wide rear)

Speed and heat are more driving factors to tire PSI. Slow driving then sure you can have that much of a PSI spread, but at highway and faster things change very quickly... throw some tight turns in there and it compounds further more.

Regardless of weight, on the highway your dealing with heat. If you're tires are sitting at different PSI front and rear, the tires with the least amount of PSI are going to heat up more quickly and become more hot...again same rim width front and rear. Tire science is fun, learned lots by trial and picking tire guys brains on the race track...start messing with thermal heat guns and tire warmers....

Even with BFG All-Terrains, 30F and 30R is pretty much the norm but it depends on weight, and rim width. You're on stock rims where John's on aftermarket rims. The different width will also dictate your tire proper PSI.

First drawing is not enough tire pressure, Second is too much, last is just right!
http://www.jeepfan.com/tech/TirePressureChalk/TirePressureCutAway.jpg

I run 29F and 29R on the Tacoma and that's with an even tire wear right across the tread. But I've varied from 25-35psi and had the most even wear at 29-30PSI. At anything lower than 27 my tires would steam in the cold from getting too hot on the highway plus I'd have scrubbing on the sidewall of the lugs.

Good questions though April!

Your tire will say what the Max PSI on the sidewall. If you'd like you can do this test at 30PSI.. Take a piece of chalk and draw a line across the width of your tire from edge to edge. http://www.jeepfan.com/tech/TirePressureChalk/TirePressureChalkLine.jpgDrive on dry pavement for about 1k. Check to see if the chalk has rubbed completely off or if there's lots of line left except for a missing part in the middle.

The right amount of chalk would be about a CM on each edge of the tire. http://www.jeepfan.com/tech/TirePressureChalk/TirePressureProper.jpg

Keep adjusting the tire pressure to get the right amount of chalk. Chris F. has my compressor if you'd like to use it.

Here's some great additional reading from 4Crawler. Roger Brown has been around for ages and has great info. Kinda dry reading but may help a bit

http://www.4crawler.com/Diesel/Tires.shtml

[Dante's Taco]

Good stuff!

Up until recently, it's been hard to do a chalk test (no dry pavement unless go out to hiway, and I never think of it then), so I haven't had a chance to chalk test my Hakka LTs yet. But that bit about needing higher pressure for LT metric vs P-metric tires has me wondering:

Blake or Nathan: So yes, I know to get the max load rating out of my Hakka they are theoretically inflated WAY higher (like to 80 PSI for load range E), but that would be like driving on Flintstone wheels...

So for non-load carrying use, in a tacoma with an empty bed, in the winter (bump bump bump) bombing around town mostly, wouldn't it still be ok to keep them lower? As in 30-35 PSI? Even on the Hiway I don't inflate them higher. (as long as they pass the chalk test)

I'm going to chalk test them this weekend, to be sure, at both ends of that range.

[canadian bum]

I am just about through my set of BFG A/T's running 26F 20R and no issues. High speed corners tires chirping in both drifts and understeer. And very high speed highway speeds not going to say how fast but fast. The A/T's will either have a D or E load rating.

I run less in the back because of the plastic bed and I adjust according to bulge and tread contact on the road. Ape I once showed you how to set up your tires just do that my numbers I gave you should be close with the wiegth of your truck.

I have on board air so if I load the truck up or pull a trailer I can adjust the rears for the extra wieght. Different brands and types of tires require different pressures so Nathans pressures will be different then mine as well as he has wieght in different places then me. Air pressures are set up for each individual vehicle. So its best to learn how to set them up yourself for optimium traction and wear. I have seen countless tires bald in the center and lots of tread on the outside because has to be 35 psi no less cause thats what the sticker in the door says.

[Grandpa Smurf]

You should be ok at 35 when running empty. The ideal pressure for "LT" will be around 45 psi to carry the vehicle manufacturer max. load (sounds high but believe it). Only vehicle weight and driver does not put much strain on the tires but the side wall structure of the "LT" tire does require more pressure to hold a proper tire shape. Nathan has very good points and the chalk test is a good one but adjust for added load when needed. Yes, Costco @ deerfoot meadows.
Blake

[the_kernel114]

hmmm, im running 255/85/16's on a 8 inch wide rim, running 45 psi front and 40 psi rear. did the chalk test on all 4 tires and came out perfect. and that is on a bone stock tacoma.

[canadian bum]

I ran 50 and 45 in my 89 F-250 diesel and that thing weighed a ton probably close to double with the armour, slip tank, 5th wheel hitch. tires were 255/85R16 BFG mud terrians. I would occasionally tow a 5th wheel flat deck with 12 round bales on it as well. Lots of black smoke and not a lot of speed. N/A diesel.

I like the softer ride of a softer tire thats why I run my tires like I do and have not had an issue and the rubber flexes better to grip ice as well.

[freeze]

I like the softer ride of a softer tire thats why I run my tires like I do and have not had an issue and the rubber flexes better to grip ice as well.

+1, especially if it's really cold ice. Air'd down provides more grip on the ice.

[Doc McCoy]

You should be ok at 35 when running empty. The ideal pressure for "LT" will be around 45 psi to carry the vehicle manufacturer max. load (sounds high but believe it). Only vehicle weight and driver does not put much strain on the tires but the side wall structure of the "LT" tire does require more pressure to hold a proper tire shape. Nathan has very good points and the chalk test is a good one but adjust for added load when needed. Yes, Costco @ deerfoot meadows.
Blake

This would also depend on the load rating of the tire and the vehicle application, would it not?

For instance, I have C Load rated tires on my first gen Tacoma (which I run at under 30 psi),
and I run E Load rated on my heavy duty GMC 3/4 ton work truck (with the back tires at 80psi).

I won't be running the same pressures on both tires any time soon. Conversely, Chris F is running E Load rated tires on his first gen. None of those tire pressures are supposed to be the same, are they?

Am I completely out to lunch on this?

[canadian bum]

Nope your not thats why I never agree with a set pressure. The door stickers in the truck are for the tires it comes with and thats all its good for. 80psi holy what you hauling in that thing?

Oh well we can argue about tires forever. The way I set up tires works good for a truck car tires are completely different. I get even tread wear and excellent tread flex for on highway ice traction. I get better ice traction with my bald tires then some of these people with brand new tires inflated to the max.

[S/C '03 taco]

and I run E Load rated on my heavy duty GMC 3/4 ton work truck (with the back tires at 80psi).

this is the factory recommended pressure and if you look at the tire plate in the door it should also give you pressure for different weight loads...these are factory specs for a bone stock vehicle and are only a SUGGESTED PSI rating as pressures also change with elevation and enviromental conditions and tempratures , when changing parts,tires , rims...ect you change the engineering involved in the numbers on the door plate( which are only a factory suggested guide line)...hence you have to change your tire pressures accordingly.

[/QUOTE]I won't be running the same pressures on both tires any time soon. Conversely, Chris F is running E Load rated tires on his first gen. None of those tire pressures are supposed to be the same, are they?

Am I completely out to lunch on this?[/QUOTE]

i run a load rating E tire that is also 4% larger then the factory size, meaning i lower my tire pressure to remain at a smooth factory road feel when street driving....my truck's preesure plaque on the door says that factory size tires on factory rims suggested tire pressure is 26psi all around....i run my tires at about 23-24 on the street....so as to jhon running his that low on his truck is a personal prefference but i would not suggest it ..... maybe i just like my tires to last over 60,000 kms....

[freeze]

i just like my tires to last over 60,000 kms....

+1. I enjoy getting 93,000 KM out these MTZ's. :D

[jreid]

It's a small world. I was at costco south on friday gettin some "summer" tires mounted, and met Blake (badennill) @ the shop. He recommended I join CT4WD!

He's a very cool & knowledgeable guy, willing to talk tires and toyotas for hours! Sounds like he's got big plans for his FJ.

Very pleased with all of the staff & service I got at costco, and as a bonus it's walking distance from my office, which is very convenient.

I guess to stay topical, I'm running 40psi all around on my BFG ATs at the moment. I'll probably go a little softer for around town but thus far 40 feels pretty good. The ATs are quieter than my yokohama winters haha :)

[S/C '03 taco]

+1. I enjoy getting 93,000 KM out these MTZ's. :D

hey i took mine off at 72,000 kms and still had about 4-5/32 remaining....i just wanted bigger tires,lol

and i seen your tires like a week or so ago and your like a month away from showing everyone your belts

[freeze]

still 1.5mm from the wear bars! Then it's 1cm to the belts..

[Grandpa Smurf]

Thanks jreid for the kind words. I take tires very seriously. It is the last thing between you and the road. Doc, as for the load range C,D & E, they have different max pressure and yes, different max loads. Auto manufacturers design in some understeer and use tire pressure to help control this. Adjusting pressures from spec. based on the type of tire may give you a better ride but may also cause adverse handling in an emergency situation. You have to way all these factors into your decision as to what is "your" ideal pressure. Error on the side of safety!

[RiceFarmer]

still 1.5mm from the wear bars! Then it's 1cm to the belts..

It's ok if it's down to the belts. It add character to the tire, plus if it's not leaking yet you're ok. OT, I got new tires and rim one year for my Supra Turbo. My friend said his Camaro SS could do a better burnout than my car, he was wrong. In the end, I scorched my brand new Potenza's to prove a point....guys.....:o

[Doc McCoy]

Thanks jreid for the kind words. I take tires very seriously. It is the last thing between you and the road. Doc, as for the load range C,D & E, they have different max pressure and yes, different max loads. Auto manufacturers design in some understeer and use tire pressure to help control this. Adjusting pressures from spec. based on the type of tire may give you a better ride but may also cause adverse handling in an emergency situation. You have to way all these factors into your decision as to what is "your" ideal pressure. Error on the side of safety!

Doh ... I meant to introduce myself on Wednesday but you were leaving with your phone'd in Peter's Milkshake deliveries ;).

Thanks for the response. I'll have to come down and chat with you about a new set of meats for my rig.

[canadian bum]

Thanks jreid for the kind words. I take tires very seriously. It is the last thing between you and the road. Doc, as for the load range C,D & E, they have different max pressure and yes, different max loads. Auto manufacturers design in some understeer and use tire pressure to help control this. Adjusting pressures from spec. based on the type of tire may give you a better ride but may also cause adverse handling in an emergency situation. You have to way all these factors into your decision as to what is "your" ideal pressure. Error on the side of safety!

I practice emergency driving often. So that when the time comes I know what my vehicle is going to do rather than chance it. And the few times I have had to do some it's like regular driving and it doesn't even shake me up. The lower pressures bite the road better instead of skidding however they are not low enough for my specific application to blow a bead.

[freeze]

The lower pressures bite the road better instead of skidding

Not on pavement but true on ice and gravel. It's similar concept as really firm race suspension versus soft caddy suspension. You'll get a stronger bite from properly inflated tires for pavement.

Now compound is a totally different matter though which doesn't translate to a softer carcass. Stiff carcass and soft compound is a match made in heaven for the road. You fulfill a stiff carcass with the right air pressure.

Lower air pressure on the road translates to heat and more heat than what the tire is designed to run on comfortably your tire performance drops dramatically which equates to less bite on the road. This doesn't equate to tire wear as A/T's have lots of heat cycles, it just equates to less optimal grip.

Motorcycle tires are the best example of this as you don't have two other tires to save your butt especially when you're pushing it on the race track. With auto's we're lucky, the contact patch is huge but with motorcycles the contact patch is about the size of a dime-quarter. All these factors are multiplied huge so you get a great sense of what small increments of PSI changes/heat/compound/speed and wear feels like and does. I didn't have a sense of this until I emptied my brain and learned from tire geeks.

[Doc McCoy]

In a way, doesn't this apply to floatations as well?

In a motorcycle your weight is so small (comparatively) that you need to have a small patch of contact to transfer every last bit of weight to that single spot on the tire.

Same in a truck or car. Normally, why ice tires are skinnier than regular tires. The weight of the truck has not changed (from summer to winter) you want to transfer more of the weight to a smaller part of the tire to increase the pressure at that point, increasing grip.

Or am I messed up again?