Tire Question

[steve2267]

I recently replaced my '88 Toyota 4x4 with a '91 Toyota 4Runner. After a bunch of repairs / maintenance (most of which I knew about), I thought I had the 4Runner running good... but the gas mileage was so-so (only 17mpg around town on a 4banger manual). Well... last week I found out my right rear tire had a leak outside the tread... so I replaced all four tires with BF Goodrich All Terrain TA 10.5x31's.

The Toy manual said to inflate the fronts to 29psi and the rears to 32psi. The tire place put them at 35psi all around. I asked about that and was told that the 29psi / 32psi was correct for the original 225R75 (whatever) tires, but that BF Goodrich recommends 35psi for my vehicle (or for their tire).

Question: what should I run my tires at on this 4Runner? Should I run the rears slightly higher than the fronts?

[A Ricci]

What does it say the max. is on the side of the tire?

What type of driving do you do? Mostly on road or do you go down dirt roads and do light off roading (like construction sites -- mud etc.) on a normal basis?

If on road mostly I still go with harder is better?? I have a GMC Sierra and I run them as hard as it says on the tires. I only drive it on road and even though the rear end is lighter I still run even pressure all around. I get very even wear and decent traction. Just a side note: My theory on pick ups or any trucks -- if you drive them fast you really need to be smooth for obvious reasons. It really fine tunes your sense of feel and smoothness. You should be twice as good in the car. This mind set relates to why I run my tires hard on the street, just the way I drive. I like to squeeze out just a little more performance out of my vehicles. However, this doesn't mean my style will fit your needs. But if you have to brake corner or swerve for safety it is better to have a harder base underneith you in order to hold back that added weight.

Try it with the toy's recommended limits then try it at 35 and then try it at the max. limit is says on the side of the tires.

Let me know what differences you notice??

[steve2267]

Try it with the toy's recommended limits then try it at 35 and then try it at the max. limit is says on the side of the tires.

Let me know what differences you notice??

The tire store guy said that the Toy recommended limits were for the smaller, factory tire size (225/75R15), and that with the larger 31x10.5 tires on the wider 7" rims, they (his store?) recommends 35psi all around. For the past few days, I've liked the way it rides @ 35psi all around. I'm not sure I'll go down to the 29psi front / 32psi rear that Toy specified in the owner's manual. I'm guessing that the tires, being LT rated tires, are rated at 50psi. Not sure I want to run them that hard. What do you think of 50psi? Might that not give uneven tread wear -- wearing out the centers first?

Most of my driving is mixed city and 5-10 miles of highway driving every day. Once a year she'll be going hunting. A week of logging roads in Colorado high country etc. Also, only the major arteries get plowed here in the Denver metro area when it snows. So all side streets will not be plowed, and many major streets will not be scraped as clean as you are used to back east. I'm not sure how tire pressure affects snow / slush / hard packed / slick road performance.

[steve2267]

Anthony... whilst I have your attention regarding my tires... might I ask your advice on shocks? I'm probably going to replace all the shocks on the 4runner soon. The vehicle has 182000 miles, and I'm not sure if the shocks have ever been replaced. She seems to cycle one or two too many times when going over a good bump. Any opinion on what kind of shocks I should go with? Air shocks? Adjustable shocks?

Also, a local 4x4 shop said I can put a "load leveling" air bag system in the rear springs (I think they are coils in the back end). So, if I load the vehicle heavy (again, think hunting -- OR -- BUGout vehicle as in get out of town the mongel hordes are coming (or a Katrina, or a ... ) )... these air bags would automatically adjust pressure to level the rear end as well as raise it. Sounds complicated to me... and I wonder it it wouldn't be a potential maintenance nightmare... but might such a system hinder or enhance handling when lightly loaded?

[A Ricci]

Steve sorry for the delay. As far as your tires go it seems like you are getting a handle on the situation. You said something about you assume the tires take 50Psi?? Not sure what you meant just look on the site of the tire, it will tell you there. If it says 35 then you are ther is it says 50 then I would put some more air in the tires but that is just my opinion.

Unfor. I do not really know much about real off road driving it is not my specialty -- sorry. So I m not sure which shocks will serve you best.

Let me know how you made out.

[steve2267]

Not sure what you meant just look on the site of the tire, it will tell you there. If it says 35 then you are ther is it says 50 then I would put some more air in the tires but that is just my opinion.


I assumed 50psi because the previous set of four tires said 50psi on their sidewall. Roger that to check the sidewall of my current tires to see what they say.

If my current tires say 50psi max... What would you run them at? 40psi? 45psi? And is that pressure measured at night or first dawn when the tires are cold? If I put 50psi in a tire that says 50psi max... during the day here in Colorado in the summer... in the heat... while driving... that pressure will be well above 50psi. Question: I thought one would only put a LOT of pressure into a tire if I was going to be near max load capacity on the vehicle? Question2: Won't driving the tires at 40-45psi (if rated for 50psi) lead to the tires wearing unevenly -- wearing out or going bald in the middle of the tread first? Or if rated for 50psi, does that mean then, that the tire and tread is designed to wear evenly all the way up to 50psi?

Say, how is your daughter? Has she arrived yet? Got any pics?

[A Ricci]

anyone interested should check out the latest copy of American Cop. I just wrote a good column on tires and the next issue will be on tire blow outs. I will have them up on my website hopefully in the next two weeks at
www.1adsi.com
There also will be my latest videos of some 53 mph jturns and a jturn with an 84 Ford Bronco.

Talk to you all soon.

[tarkio]

I am not an expert by any means but I do have some experience with trucks / suvs.

I drive around 60,000 mile per year in a pickup or a suv.

I use 10 ply tires with very high load ratings. These tires have max psi of 80. When aired up at 80, they drive terribly. Ducking and diving and responding to every bump and track and especially bad on a rough highway in a heavy wind.

What I do is back the pressure off progressively from the highest rating until I find where the vehicle drives the best. I then back off the rear tires according to the placard. meaning if the placard says 39 psi front 35 psi rear and if I find that the vehicle handles well with 48 psi in the front then back the rear tires of 4 pounds.

What I think I have figured out is that the optimal tire pressure depends a great deal on the softness/stiffness of the suspension and the wear in it. This is my assumption.

I do up the pressure when hauling a lot of weight in the bed or pulling a gooseneck trailer. I will also back the pressure off if I am in heavy snow or sand.

I have run into this problem especially in 1/2 ton pickups that come with lightweight tires pressured up to 35-38 psi and then I replace these with good 10 plys with a lot higher load rating.

Again, this is my opinion and you should be really careful when adjusting pressures like this.

If I have missed something or you think I am wrong, let me know. Because I do drive so much and a lot of it is at very high speeds (I know this isn't smart but when you drive this much it is just about required), I am always looking for guidance in bettering my driving skills.

Thanks
Matthew

The info you just read is about worth what it cost you to acquire.

[Brownie]

tarkio,

Welcome to the forum sir. Feel free to post on any thread or start your own if you like.

Stay sharp

[RTBRANE]

Hi tarkio,
The max psi marked on the tire is used to reach the rated weight also marked on the tire. The sticker on the door/door sil will give the axle weight rating for the vehicle. If you check with the tire manufacturer, they will most likely have a recommended pressure for front and rear location on your vehicle. If they don't, it may mean that the tire is not intended for that application. They can also give you this info, probably at the same time. If they seem puzzled about the use of that tire on your vehicle, take that as a sign that you are using the wrong tire! Or, the wrong brand, perhaps.
Will