Mojave Trail?

**daveb** · 12-24-2012, 09:15 PM

OK, so I went down south last week to do the Mojave Trail. My buddy Don was able to get away from the family provided we were back before Christmas. Unfortunately I failed to call ahead and ask about the conditions. The internet showed good weather but it was wrong for the area. After seeing puddles, a quick phone call told the story, "we've had rain and snow". It was a bit puzzeling, yet because I've never been there I didn't know what to think. You're supposed to start at the Colorado River, pick up a rock and head west where somewhere in the mid portion of the trail you drop it off at a specific spot. Well, that never happened. We figured the little 15 mile stretch around Baker would be fine for the first night because it was dry there.
Now I've been in some sand, but

Is the whole trail that bad? How bout those dry lakes? Yep, we never aired down but it was 15 miles of "I hope it doesn't get worse"! It was as bad as pulling a steep grade...ARR..ARR..ARR..ARR..ARR, for 15 miles.

The rangers suggested that driving through the dry lakes was not a good idea. After driving though the western wash, I'd hate to think what the dry lakes would be like in good conditions.

So the big question is whether this "easy" trail is suited for a 11k lb vehicle. Anybody done it in a heavy SMB? The mud terrains tires seemed to dig in. I still wonder if airing down would have helped much. Would have been bad to pop a bead being by ourselves. I was haulin ass though there

I want to go back though thats for sure. It would be a great group run if it's doable!

**Gooseberry** · 12-24-2012, 10:20 PM

Ya it's a easy run and did it in a snow storm. The lake bed was to soft so we drove in on the west side.

Yes airing down would have been a good idea for your comfort and traction.

Tapatio · 12-24-2012, 10:32 PM

Only the first 16 miles is sandy Dave...

It does get much easier once you get past the floodplain. 80% of the trail is hard pack, no problem for a SMB. The last time I took the trail I had my Toyota Landcruiser/tent trailer. Couldn't imagine getting through the first section without airing down.

CJ · 12-24-2012, 11:10 PM

Did it a year or two ago, didn’t seem hard. Had to short cut the lake bed, it was still a bit too wet from recent rains. Snowed on us the first night We started in Barstow and ended at the river.

All in all it was a great time.

Pschitt · 12-25-2012, 03:04 AM

Quote:

Originally Posted by daveb

The mud terrains tires seemed to dig in. I still wonder if airing down would have helped much.

Definitely yes! Remember : the pressure that a tire applies on the ground is equal to its inflation pressure, regardless of the weight of the vehicle.
So, if you inflate 70 Psi, your tires press 70 Psi on the ground but if you deflate those to 25 Psi, they only press a third on the ground. That makes a big difference in soft terrain...

yvrr · 12-25-2012, 08:54 AM

Quote:

Originally Posted by Pschitt

Quote:

Originally Posted by daveb

The mud terrains tires seemed to dig in. I still wonder if airing down would have helped much.

Definitely yes! Remember : the pressure that a tire applies on the ground is equal to its inflation pressure, regardless of the weight of the vehicle.
So, if you inflate 70 Psi, your tires press 70 Psi on the ground but if you deflate those to 25 Psi, they only press a third on the ground. That makes a big difference in soft terrain...

I don't think that is correct. If your vehicle weighs 10,000 pounds, then there is an average of 2,500 pounds per tire. If the tire "footprint" fully inflated is 6" by 6" or 36 square inches, then the tire has a force of 69 pounds per square inch. If you air down, you increase the footprint and thus reduce the pounds per square inch. Whether you air down or not, the entire weight of the vehicle has to be transferred to the ground.

Pschitt · 12-25-2012, 09:14 AM

Quote:

Originally Posted by yvrr

I don't think that is correct.

Hello yvrr. I can certifie that it's correct. I worked for years by Michelin tires as technical engineer and technical advice to users was a part of my job. Pressure on the ground is always the same as inflated pressure, it's a law of physics for every flexible and inflated tire (excepted some approximation due to tire carcass flexion which are virtualy negligible)...

You're right : when you air down, footprint increases since pressure decreases and weight per tire stays the same. Because equation is : weight / surface = pressure... If weight is constant, deflating tire (reducing pressure) makes surface increase. But pressure doesn't depend of weight : if you increase weight and don't inflate tires, pressure stay the same and surface increases...
Many people find it difficult to understand but it's so : ground pressure under an inflated tire is always the same as inflated pressure, regardless of weight on it (of course without exeeding tire resistance limit).
This is also why tires manufacturers developped very low pressure tires for agricultural tractors, reducing ground compactation for better agricultural productivity...

**daveb** · 12-25-2012, 02:18 PM

After it rained I wouldn't think the Manix/Mojave River wash would have been any trouble at all. Water and sand are good together. Coming out of the wash into Afton wasn't an issue and the trail improved big time. I was more worried about the the dry lake beds that were ahead of us and didn't have a clue you could drive around them. Typical of rangers trying to scare you out or not letting you know about detours. The rain was heavy throughout the early morning so I felt better to abort the trip. Really the only section I was worried about due to wet weather was the area that has the deep ruts. According to what I researched about the trail, the ruts are the most difficult part and not even 4x4 worthy, but then again it never said anything about the deep sand that the Manix wash holds. That sand was worse than any beach I've been on. Even the dirt bikes that had been through there had sank a good 10" into the sand.
Now I wish we would have just started at the Colorado River. Maybe come back real soon to do the whole route but at least I'll air down for the last part of it.

Thanks for the info.

yvrr · 12-27-2012, 08:41 AM

Quote:

Originally Posted by Pschitt

Many people find it difficult to understand but it's so : ground pressure under an inflated tire is always the same as inflated pressure, regardless of weight on it (of course without exceeding tire resistance limit).

I took a lot of physics and engineering classes while in school and the weight is obviously a factor. If you let all of the air out of all four tires, that wouldn't mean that the van was weightless. If you removed a tire from the van and set it on the ground vertically, it is not going to exert as much force on the ground as when it was on the vehicle.

I guess that we going to need to agree to disagree.

**macmcintire** · 12-27-2012, 10:04 AM

What? Math and science are not absolutes? Say it isn't so? What are the statistical odds of that? Say what? Statistics aren't absolute either? What is this world coming to? I would weigh in with my opinion, but some might argue that my opinion is wrong -- which, of course, it never is.