Driving with Grey tank full

[itchn2go]

Did not have a sewer connection this past weekend at the campground and the road to the dump station had lots of branches hanging over the road. Since I have a sewer connection at home I opted to drive home with the full tank.

Well, to me the front end seemed light and often times the coach had a mind of its own and I feel this was due to the water sloshing around.
First and last time I'll ever do that...(slap)  But we had a great time...Be safe.

 

[Marc L]

I guy on another forum did that too, he lost control and rolled over the truck and trailer.  Family of 4 survived with minor scratches and dirty underwear.  Also the last time they are doing that.

 

[thatcrazyfamily]

I don't think I fully understand...  If you normally drive with a full fresh water tank and it does fine then if the fresh water tank is empty and you have a full grey and black water tank what's the difference?  Are they placed in much different places?  Perhaps I'm missing something.

 

[John Canfield]

Full tanks on our Horizon are only an issue as far as weight is concerned.  We have traveled with full water or gray before, but I'm always cognizant of our remaining CCC.  We generally run 500 pounds under capacity with full diesel and 15 gallons of fresh water, so we're good to haul around 60-70 gallons more liquid.

 

[SargeW]

John is right, there should be some minor differences in handling but there is no danger of driving with tanks full other than to have reduced power available and reduced fuel mileage.  I also never drive with a full water tank for those same reasons. I usually run with 20 gallons or so in case the DW needs the restroom (all the time).  If someone rolled a trailer, there were other factors at work there.  Most likely the experience level of the driver.

 

[seilerbird]

The weight of the water in your RV has nothing to do with your gas mileage. People who drive a large RV report that adding a 2000 toad will lose them about a half a mile per gallon. A few hundred pounds of water just won't make a difference.

 

[Roaddog]

I don't think I fully understand...  If you normally drive with a full fresh water tank and it does fine then if the fresh water tank is empty and you have a full grey and black water tank what's the difference?  Are they placed in much different places?  Perhaps I'm missing something.

I think the difference could be where that weight is located. Mine has the water tanks in the middle of the rv, pretty far ahead of the rear axle. The holding tanks however are a good distance behind the rear axle. If you shift the weight of that fresh water from the middle of the rig, which is the ideal load zone, to the far rear of the rig, I think it could indeed lighten the front end somewhat, especially on longer rvs that have a lot of rear overhang which translates to leverage.
But , I'm new to motor homes so I'm not talking from practical experience, just theory. In other words "whado I know?"

 

[Pierat]

I've heard that some RVs have tanks that are placed very poorly for balance if they are not nearly empty all the time. I think that was in a Life on Wheels weight seminar a couple of years ago. Might be worth getting wheel or at least axle weights with tanks full and empty, to know what you're dealing with.

 

[seilerbird]

I have driven many different motorhomes both full and empty and I sure can't tell any difference in the handling. If the weight were located up real high on the rig it would be a different story.

 

[cbeierl]

Looking at the plumbing diagram for the 05 Journey 39K the the black and gray tanks are amidships, ahead of the rear wheels.  I think it unlikely that one could tell the difference between a full and empty tank while driving.  I suspect that something else was happening--perhaps tire pressure issues?

 

[John Canfield]

...  I suspect that something else was happening--perhaps tire pressure issues?...

That would be my take as well especially since it was a travel trailer involved in the previously mentioned accident.  I have seen trailers wag the tow vehicle almost to the point to where the driver lost control.

 

[SargeW]

The weight of the water in your RV has nothing to do with your gas mileage. 

I disagree.  Any weight you add to a MH, car, or bicycle takes extra energy to get it going.  Simple laws of physics.  Now it will take less if you get on an interstate for 300 miles without stopping.  However, stop and go driving and hills take a significant amount of energy to move weight.  I hold 100 gallons of fresh not counting propane, fuel, and holding tanks.  That fresh tank alone would be 800 pounds if full.  That would definitely add to the HP requirements to get it going.

 

[itchn2go]

We were hooked up to camground water just no sewer so we did not displace any fresh water. We added a lot to the grey water tank (2/3+)and not very much to the black tank. Tire presssure was fine as I check it every time we leave home.
The rig just acted a little squirrley to me and I won't drive with a full waste water tank again if I have a option.

Towing a toad is another matter. Personally I can tell that the toad affects acceleration and braking and certainly bouncing when we hit some bridges. Not that is not acceptable while towing, just that I know its back there and the coach handles better without it...Be Safe ;D

 

[Gary RV_Wizard]

I'm struggling to accept that transferring  50-60 gallons of water from fresh to gray & black could cause handling problems on a coach of that size and weight. Even if the waste tanks are behind the rear axle, which would be rare indeed on a diesel pusher.

It is my opinion that the blame for the handling problem ought to be assigned elsewhere.

 

[Marc L]

I guy on another forum did that too, he lost control and rolled over the truck and trailer.  Family of 4 survived with minor scratches and dirty underwear.  Also the last time they are doing that.

I wrote that because I assumed a trailer, just noticed we are talking about a motorhome, so my post does not apply here.  If an admin wants, they can delete my post.

 

[John Canfield]

Naw - you're fine with the post Marc  , brought out some good discussion.  I do think this thread belongs in the Motorhome board though since it can apply across different manufacturers.

 

[Richard 34A]

I'm struggling to accept that transferring  50-60 gallons of water from fresh to gray & black could cause handling problems on a coach of that size and weight. Even if the waste tanks are behind the rear axle, which would be rare indeed on a diesel pusher.

It is my opinion that the blame for the handling problem ought to be assigned elsewhere.

I'd agree with this reply; if there was an issue, wouldn't there be a 'warning' label not to drive with a full water tank, or a full grey-water tank, or both? I'd say I might have a slight loss in performance and fuel economy, but would I notice it? Not really... Handling-wise, can I tell driving my MH when the 75 gallon fuel tank is full or almost empty? Not me...

 

[Marc L]

I have seen a Winnie at the campground this weekend, not sure which model, I was not that close to it.  One thing I noticed is that the overhang behind the rear axle was almost as long as the wheelbase.  Depending how far back the tank is, couldn't it change the way it drives?

 

[milo30]

Could your fresh water tank have baffles to help with the sloshing and the grey water tank not?  I could see something like that being noticeable

 

[Gary RV_Wizard]

I suspect a tank all the way in the rear on a long rear overhang would have some effect, but I doubt if any are located back that far.