Scary Crosswinds: How much is too much???

J_KHawthorne · 10-09-2013, 08:56 PM

When I hit 65, (a couple of years ago), I came to the startling realization that many things that never used to faze me, suddenly made me want to look for those big, huge blue "Rest Area" signs...

Thunderstorms, tornadoes, hurricanes, Kansas drivers (no offense... they seem proud of the fact), blizzards, and torrential rains were the worst culprits, but pulling a 5'er in crosswinds started to move higher and higher up the scale, too.

First year towing, I chickened out and started looking for an RV park or WalMart after the crosswinds hit about 15mph. That was okay; last year we spent a few nights in Guernsey State Park in WY that we will never forget... a cool golf course and nice folks. (Crosswinds have no effect on my golf game... but then again, I don't keep score.)

Anyway, getting to the point here; how much wind does it take to tip over a trailer???

Ron Gratz wrote several years ago in RV net, and it's worth a repeat:
the formula can be easily entered into an Excel spreadsheet.

Ron's formula

V = SQRT(W*b/(0.00666*l*(h-h2/2)*(h/2+h2/4)))

"where...
V = wind speed required to tip over trailer, mph
W = trailer weight, lbs
b = trailer width (tire center-center), ft
l = trailer length, ft
h = trailer height (from ground), ft
h2 = tire height, ft

For example, with W=8000#, b=8', l=30',h=10',h2=3' -- the calculated overturning wind speed is 81 mph.

As expected, the most sensitive factor is trailer height. If the height is increased to 12', the overturning wind speed reduces to 67 mph.

The above equation does not account for any yaw instability effects. It only considers the simple blow-over effect. Wind-related accidents can occur at much lower speeds due to yaw instabilities. In that case, the effect of greater height of a 5er would tend to be offset by its more stable connection to the TV."

Gave me somewhat more peace of mind... (my static V is ~68mph)

But I still slow wayyyy down in x-winds above 20 mph!

nducker23 · 10-09-2013, 10:05 PM

when we got our 25rr grey wolf we pulled it across Nebraska with a cross wind. it really raised my awareness cause of the more surface area I had, but when I see trucks start pulling off interstate I pull off.

dalford · 10-09-2013, 10:40 PM

Wow, that is amazing. I live in Florida and when winds get up to that level we are having a hurricane and the bridges and roads are closed. I would never try to drive in those conditions with or without a TT. But then again I am from Florida and don't experience the kind of winds you in Kansas City area might experience. I plan on taking a trip out to the west coast at some point. What kind of winds can I expect as a norm.

Nducker, good point on the semi's. if the professionals are getting off the road I sure don't belong out there.

J_KHawthorne · 10-09-2013, 11:08 PM

Quote:

Originally Posted by dalford

Wow, that is amazing. I live in Florida and when winds get up to that level we are having a hurricane and the bridges and roads are closed. I would never try to drive in those conditions with or without a TT. But then again I am from Florida and don't experience the kind of winds you in Kansas City area might experience. I plan on taking a trip out to the west coast at some point. What kind of winds can I expect as a norm.

Nducker, good point on the semi's. if the professionals are getting off the road I sure don't belong out there.

The winds out west Kansas and down into the Oklahoma panhandle around Guymon have never been less than 12-20mph anytime I have been through there on hwy 54. When they're tailwinds, all is fine and dandy; headwinds hurt the gas mileage, but are manageable.

The Weather Channel has a good ap for the iPad that gives you current conditions on the road ahead and you can plan accordingly.

I regularly call it quits if the 90 degree crosswinds exceed 20 mph with any gusts at all, and quartering winds above 25mph. Main thing is, if you're not having fun, then it's time to park it.

dalford · 10-09-2013, 11:54 PM

Jim & Kathy, thanks for the info on winds. In Florida the main highways pretty much run north and south and we always have the sea breeze which is east/west. Usually less than 20 mph, more like 10-15 mph. I have not experienced winds greater than 20 that I am aware of. My wife and I pulled from Fl to Prince Edward Island, CN and back this summer without issue on wind so I look forward to that experience. I agree, if it is no fun, find the next rv park to wait it out.

You mentioned an app. Do you recall what it is called....

J_KHawthorne · 10-10-2013, 12:45 AM

Quote:

Originally Posted by dalford

... My wife and I pulled from Fl to Prince Edward Island, CN and back this summer without issue on wind so I look forward to that experience. I agree, if it is no fun, find the next rv park to wait it out.

You mentioned an app. Do you recall what it is called....

It's just "The Weather Channel" and I believe Kathy got it free from their web-site, or free from the app store. I really depend on it on the road; only hassle is it will store just 10 locations. But it has been extremely reliable for us, and I just quickly load several en-route locations in every night.

The mid-west is famous for windy conditions, but we have found that the winds are usually worse in the mid-afternoon. Several times, we have made early starts with a mid-day layover (siesta) and continued on later in the day. Watch for dust storms across NM and AZ on I10. (usually out of the SE.

J_KHawthorne · 10-10-2013, 01:00 AM

BTW,
I applied that formula to me struggling with a sheet of 1/2 plywood 4'x8' held 2.5' off the ground. It says I would be blown over in a 17mph wind cold sober. Sounds about right.

BarryD0706 · 10-10-2013, 08:19 AM

I note that you're towing a 5th wheel with a Toyota Tundra. I really believe that this is a large part of the problem.

**ependydad** · 10-10-2013, 08:39 AM

Quote:

Originally Posted by BarryD0706

I note that you're towing a 5th wheel with a Toyota Tundra. I really believe that this is a large part of the problem.

I'm not sure that's a fair statement. Given this camper's pin weight percentage (15%), even fully loaded - they're only looking at 1,700 pounds of pin weight. With 3,000 pounds of carrying capacity in a 31' trailer- I'd be pretty impressed if they were able to load it to the gills and achieve that.

Their pin weight is only somewhere between 1,200 (dry) and 1,700-1,800 (max) pounds.

On top of that, it's a couples trailer and the statement that 65 was a couple of years ago, there isn't a crap load of kids and kid-related paraphernalia in the truck.

I don't think we have nearly enough information to make a broad-brush statement like you have.

Scratch · 10-10-2013, 09:20 AM

I'm with Barry on this one. I love me some half ton trucks, (Tundra just might be the best of all of 'em) but they just don't have the stiffer suspension found on 3/4 ton TVs and up. We've pulled with both, and the difference is night and day in terms of towing stability.

another_newfie · 10-10-2013, 09:38 AM

Derail about undersized trucks aside (I also believe he is in over his head with this combo), I don't think I could give a hard and fast rule about crosswinds. I will say I've hauled in all sorts of weather. I have pulled over in a rest area or other safe place a few times. Usually though due to snowy conditions (we winter camp and often haul in the snow). For me it's not the winds so much as visibility that will determine when I pull over.

rattleNsmoke · 10-10-2013, 09:46 AM

Unfortunately, myself included have been guilty of 'get home itis' and we push on no matter what. That is when we can be subject to a severe crosswind and a accident in the making. Most of the time accidents are a series of wrong decisions leading to a final unfortunate conclusion. If winds are forecast to be VERY gusty and you see semi's parked, do the same. Weather will change.

jtstromsburg · 10-10-2013, 09:59 AM

There are too many variables, in my opinion, to use that formula. Drw. Full or empty tanks, etc etc. I've towed with my 3/4 T. 40' fiver, 12 1/2' tall, in some serious winds(approx 30 with gusts to 50) and felt very stable. But with my old camper, 28' 10' 6" tall, been blown all over the road in 20mph winds with the same truck. I've purposely left tanks full, towing in winds as the ballast really helps.
I agree with the statement about shutting down when the big boys do.

Stay safe and have fun
Happy Campin!

sail2liv · 10-10-2013, 10:10 AM

Variables are just way too many to fix a speed to anything.....but wt and distance are somewhat consistant....we tow with the longest wheel base possible and the biggest truck available....which for us and the weight we tow is the Chevy 2500hd commercial crew cab with 8 ft bed....most of the time never know the trailer is back there....but terrain and bridges over rivers can funnel a 20 mph wind to great impact speeds....we tow around 7000 lbs to 7500 in a 26 ft box 5er....the truck runs around 22 ft and gross out around 8000 lbs with the pin wt....wheel base probably around 16 feet,,,,....combined weight is usually 15k - 15.5 k ...speed driven 56-58 mph.....
on a 1500 mile trip the trailer might wiggle once.....enough to feel not enough to be dangerous...but we don t travel on wet roads and thunderstorms if possible...and other adverse conditions cause us to stay put.....and I can say everyone passes me on a trip like that....so I have a good view and know will be posting about Chinese tires....good luck to all who tow....

Oakman · 10-10-2013, 10:23 AM

Coming back from the Washington D.C. FROG rally earlier this year we hit crosswinds of 25 MPH gusting to 35 MPH. At one point the crosswind was strong enough to actually blow the steps extended on our fifth wheel. The only way I could tell we were in heavy winds was how far I had to push down on the accelerator, other than that the ride was very stable. I believe if the OP would move up to a ¾ ton truck he would see/feel a world of difference.

ryand · 10-10-2013, 10:27 AM

A few years ago one of my very first towing experiences was from St. Louis to Kansas City in April through an approaching cold front with winds gusting to 40mph. While the majority of those were head winds every once and awhile the combo would get hit from the side and really cause me to freak out.

Couple my inexperience with towing a RV and the fact that my hitch set up was not dialed in yet it made for a very stressful ride.

jevanb · 10-10-2013, 10:46 AM

Quote:

Originally Posted by jtstromsburg

There are too many variables, in my opinion, to use that formula. Drw. Full or empty tanks, etc etc. I've towed with my 3/4 T. 40' fiver, 12 1/2' tall, in some serious winds(approx 30 with gusts to 50) and felt very stable. But with my old camper, 28' 10' 6" tall, been blown all over the road in 20mph winds with the same truck. I've purposely left tanks full, towing in winds as the ballast really helps.
I agree with the statement about shutting down when the big boys do.

Stay safe and have fun
Happy Campin!

I am the same as you and could not agree more, got blown around more with the TT then the 5er. plus I find that if I air the bags a little more the sway lightens up a bit. but towing with a soft rear 1/2 ton would not be my choice IMO

dalford · 10-10-2013, 11:31 PM

Jim, I appreciate your post. I guess it is because of my engineering background. Seems to be a bad thing on this forum. i certainly did not think you were suggesting anyone use that formula as a hard and fast rule but as an interesting point of information. I guess I missed the part where you were asking for anyone to fix a problem for you, but you sure got em.

I see you have towed over 13000 miles and are in control of your ship. You also know when to get off the road. Thanks for the post and keep em coming....

Timtation · 10-10-2013, 11:45 PM

Down in Amarillo several years ago it seemed the wind just never quit. I asked an oldtimer I was working with, "Does it always blow this way?"
After a studious pause he looked at me very seriously pointed to his left and said: "No, sometimes it blows that way."

RetAFRVnW8 · 10-10-2013, 11:53 PM

Just towed my new 45'6"L x 12'3"H Cherokee from Minnesota to Texas and at 37yrs young, I can say Kansas had me looking for a rest stop quick!! As awesome as that formula is, my seat of the pants math told me when enough was enough! LOL And when I'm on the far right of my lane and the tail end of the trailer is flirting with the left side doesn't help either. Yes, I know but its a destination trailer but its still got to make it to that destination. My hats off to Equalizer hitches though, that thing made all the difference in the world.

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