First long distance run on BFG MTs tomorrow.... What psi should I run them at? (1 Viewer)

[98 SNAKE EATER]

Driving from Orlando to NYC tomorrow for the first time on new 305/70/16 BFG MT's

What pressure should I be running for 90+mph speeds and minimal tire wear over 1200 miles straight?

I've done this trip countless times over the last year on 275 street rubber, but never on MT's

 

[cruiserdan]

I run the factory-specified 32 (cold) psi in my 305/70/16 Dunlops.

It is important to note that mud tires are not fond of that kind of speed, not to mention it's illegal. In addition the maximun sustained crusing speed for an 80 is listed at 80 mph (still faster than the legal limit).

 

[tblume]

I ran 265's on the work truck; '05 chev HD, 7500 pounds loaded, D range tires @ 55psi , they lasted me 30K, would have been more but logging roads took their toll on the casing I usually run in the mid 70's though, so your speed (heat) will accelerate wear I bet. watch for mid corner bumps, the a$$ end would get squirmy at highway speeds, and the drone made me sleepy after a full day of I-5.

good tires all around though, I'll get another set if these Micky T ATZ+'s would ever wear out.

 

[98 SNAKE EATER]

I run the factory-specified 32 (cold) psi in my 305/70/16 Dunlops.

It is important to note that mud tires are not fond of that kind of speed, not to mention it's illegal. In addition the maximun sustained crusing speed for an 80 is listed at 80 mph (still faster than the legal limit).

Illegal's my middle name

I've been running the factory 32psi since I got them a couple weeks back, but this is what the Tire FAQ lists:

275/70/16, 265/75/16 - 42-45psi,
285/75/16, 305/70/16 - 40-42 psi,
295/75/16- 38-40psi,
315/75/16- 36-40 psi.

 

[-Spike-]

Link to that FAQ? Can't find it in the index. Odd that there would be a chart that ignores load rating, vehicle weight, tread composition, and manufacturer's suggestions and is instead based entirely on size.

-Spike

 

[98 SNAKE EATER]

Link to that FAQ? Can't find it in the index. Odd that there would be a chart that ignores load rating, vehicle weight, tread composition, and manufacturer's suggestions and is instead based entirely on size.

-Spike

https://forum.ih8mud.com/80-series-tech/114057-tire-right-me-faq-tire-information.html



Also says "You should not go below the minimum pressures above. If you have a truck that has a lot of extra weight (i.e. sliders, bull bar, winch, bumpers, etc.) add 5-8psi to the above."

 

[cruiserruf]

15 psi for maximum traction

 

[corsair23]

Link to that FAQ? Can't find it in the index. Odd that there would be a chart that ignores load rating, vehicle weight, tread composition, and manufacturer's suggestions and is instead based entirely on size.

-Spike

https://forum.ih8mud.com/80-series-tech/114057-tire-right-me-faq-tire-information.html

Also says "You should not go below the minimum pressures above. If you have a truck that has a lot of extra weight (i.e. sliders, bull bar, winch, bumpers, etc.) add 5-8psi to the above."

Please keep in mind this important "tidbit" that the FAQ was developed around:


Summary of Tire Pressure-

The Stock 80 uses a P-metric tire (designated by the use of a P in the size i.e. P275/70/16), with a recommended inflation pressure of 32psi. When converting to a light truck tire (LT) which most A/T and Max Traction tires are (LT is designated on the sidewall next to the size i.e. LT275/70/16), you should add approximately 10psi to the factory recommended pressures. Based on the load charts (and this doesn't matter whether you are running a C, D, or E rated tire) you should adjust your base pressure to be as follows when changing to an LT tire:

 

[-Spike-]

I'll just quietly disagree with what's posted in the FAQ. I know a lot of time went into putting that together, and maybe the source knows something I don't. I don't know where Romer got the info. My personal experience is to start with what the tire manufacturer recommends, factor in if the tire is rated for far more weight than I'm carrying, and then monitor the tire heat and tread wear over the first couple of thousand miles to come up with what's best for my particular vehicle/tire combo. Your idea of asking other people with similar setups is good, hopefully you'll get more answers along those lines.

-Spike

 

[fjfar80]

Just remember that you are not the only one on the roads and 90+ may not be the safest speed for a Land Cruiser and you never know what someone will do when they see you flying up behind them or at them. It's not like a Land Cruiser responds to steering inputs or abrupt braking at 90+ like an Audi RS4. My suggestion, stick it around the 75mph mark and remember that accidents do happen. At 75 you are only adding 2 hours to your journey (compared to 13.5 total hours at 90+) but, you are at a much safer speed. I lost a friend due to a rollover at high speed and he would still be alive if the driver was going the speed limit (per the accident investigation). So, take your time man...an extra two hours is not worth your life or someone else's life.

 

[-Spike-]

Another bit of ad-hoc advice- if you want to run at high speeds, more pressure is going to help with body roll and give you more feel for the road, but may adversly affect braking and cornering traction. I cringe when people get on a soapbox about driving habits, but truly in this case, the vehicle and tires aren't the best choice for high speed maneuvers.

-Spike

 

[Devil's Slide Doug]

I run the factory-specified 32 (cold) psi in my 305/70/16 Dunlops.

the maximun sustained crusing speed for an 80 is listed at 80 mph (still faster than the legal limit).

I had always figured that the number in the fj series was exactly a reference to your cruising speed. 55, 60, 62, 80, etc.

 

[e9999]

I have already said recently what I run mine at for long distance fuel saving runs... Some disagree.


But I'll add that the notion of using the sticker pressure listed for a stock truck with street tires in turn for a much heavier armored truck with offroad tires seems to me to be questionable at best...

 

[Nay]

I'll just quietly disagree with what's posted in the FAQ.

I'll loudly disagree

We've had a lot of debate out this, and what is missing by going to much larger tires is how load rating drops as PSI drops. I think Cary is the sponsor of this part of the FAQ, and he agrees that we don't have this info.

So, if my tires at max PSI of 50 have a load rating of 3,500 lbs then what is the rating at 30 PSI? The only reason to run near 40 PSI is an assumption that load rating is dangerously low at any PSI less than this, an assumption that is not based on any factual data.

My rig is undriveable at those high PSI - my tires don't have a flat tread and it runs way up on the center of the tread at high PSI. It runs best across the board at about 30 PSI.

Unless you can find a chart that shows load rating for your tires across PSI, I'd run them around the factory recommendation. I hear of people running 45 PSI in big MT's and that must just be hell around town. I wouldn't do that because the FAQ says so.

In fact, I wouldn't do much of anything based on the FAQ

 

[cruiserdan]

F requently
A in't
Q rect

?

 

[Nay]

F requently
A in't
Q rect

?

 

[Hants]

Just remember that you are not the only one on the roads and 90+ may not be the safest speed for a Land Cruiser and you never know what someone will do when they see you flying up behind them or at them. It's not like a Land Cruiser responds to steering inputs or abrupt braking at 90+ like an Audi RS4. My suggestion, stick it around the 75mph mark and remember that accidents do happen. At 75 you are only adding 2 hours to your journey (compared to 13.5 total hours at 90+) but, you are at a much safer speed. I lost a friend due to a rollover at high speed and he would still be alive if the driver was going the speed limit (per the accident investigation). So, take your time man...an extra two hours is not worth your life or someone else's life.

Adding to this a bit: I've been testing changes in driving habits versus mileage, and have found 1) setting cruise at 65 versus 75 increased MPG by 1-2, and 2) keeping the RPM under 3550 when under load keeps the (my?) engine in closed loop and increased MPG by ANOTHER 1-2. I recently obtained 17.2 MPG on a 280 MI trip over the continental divide.

At current fuel prices, those changes can add up to real dollars over a long trip.

 

[Brian894X4]

I have already said recently what I run mine at for long distance fuel saving runs... Some disagree.


But I'll add that the notion of using the sticker pressure listed for a stock truck with street tires in turn for a much heavier armored truck with offroad tires seems to me to be questionable at best...

I totally agree. We're talking different tire sizes, different load ranges and different brands than the factory, not to mention different overall weight and setup. Plus even the same tire size from different manufactures will have widely varying pressure specifications. The same size tire can vary from 30-80 max psi depending on manufacture.

The 305 BFG has a max psi of 50. Depending on your weight, somewhere around 40-45 psi might not be a bad idea, but that's only a thought. I don't run those particular tires or know how your rig is built.

 

[fjfar80]

Spike -

Trust me I did not intend to be on a "soapbox" I just know that SUVs (with the exception of a Porsche Cayenne GTS or Turbo) are not specifically designed for high speed maneuvering and the handling characteristics resulting from unexpected high speed maneuvers can literally be deadly. If he indicated he was going to drive 90+ in an E60 M5; I would have said nothing. I apologize if I came across as being on a "soapbox" but, having witnessed the results of a high-speed rollover and having handled the body bag I just wanted to add my $.02.

 

[gotmud]

Going 90+ is one thing. Stopping and controlling 3 tons quickly is another. I'm addicted to speed as much as the next guy, and certainly understand "moving with a purpose". Hell, I drifted my wife's Sienna the other day on an unopened section of freeway. HOWEVER, there is no way I would feel comfortable even with an unlifted, stock-tired 80. Keep your speed reasonable, and be around to tell us how your new BFG's did. Are they the new KM2's?