trailer tire size survey

[Citroen/Dave]

After getting up to one hundred twenty thousand miles on Michlin tires on some of my 1962-71 DS Citroen automobiles and sometimes driving on tires that were more than thirty years old I find it rather upsetting to have to get new tires on my five year old Rav 4 Toyota with only 18,000 miles on it.

[Why did I drive those tires so long? Blown tires on a DS and many newer Citroens have almost no affect on stability or the directional control, even with hands-off steering regardless of speed. Has anyone seen the movie "Day of the Jackel" depicting the assasination attempt on Charles De Gaulle and his wife?  In the actual event both tires on one side of the Citroen where shot out: the driver simply sped up over 60 miles per hour and drove the car out of town to the airport and to safety!  The high tire milages achieved on Citroens are a result of the nitrogen gas springs of the Citroen's hydronumatic suspension adsorbing the bumps rather than the tire flexing found in cars that have steel springs. (Michlin introduced the steel radial tire on the DS Citroen; the radial on the 1948 B11 Citroen.) The DS has self correcting steering meaning that you can sit on your hands at 115 miles an hour, have a front tire blow, and mash the brakes if you like: straight line stopping.  

This year the feds have mandated electronic stability control on all new cars sold in the USA.  The same effect was a standard feature in the 1955 DS Citroen achieved by good design including a three point suspension with four wheels; full time 2400 lb hydraulic power even with the loss of an engine or fan belts, for a period of time; hydraulic computers; survo feed back hydraulic control valves to inform the driver and the computers of the performance of features like the brakes, steering, and suspension; center suspended front wheel; and much more. . .  the first car with an effective antilock brake system and the first high volumn car with disk brakes, for example.] Sorry, I will get off my soap box.  My sales pitch last 2 1/2 hours, front bumper to the back bumper.

The tire industry has recently played a dirty trick on us consumers.  If you read the fine print you will find a recommendation to buy new tires after 6 years, regardless of milage.  The reason why?  Tire manufactures, including Michlen and all the other brands they now own, are using an exterior rubber compound that weathers rapidly.  

My Rav 4 SUV (Stupid Utility Vehicle) began wandering all over the road this year.  A quick inspection found circumferential cracks in the rubber between the treads, plenty of tread left, and flex cracks in the side walls.  Currently, the tire industry is using rubber compounds that begin failing after 6 years, to increase business.  It is no longer a wise decision to buy high milage car tires if you are not going to wear them out in 6 years or less.

I have no information on trailer tires.  I would keep the old one with good tread for a while longer until someone checks out the posted life span of new trailer tires.  Hopefully the tire industry has not screwed them up as well.  

[Unless you have a safe car (very doubtful) like the old 1955 DS Citroen, which was recognized in 2005 as the safest automobile ever, don't keep your recent tires longer than 6 years.]

Dave

[JTMeissner]

This summer, I made the 1100 mile trip from Newport, RI to Savannah, GA using the set-up that existed when I purchased my boat: Magic-Tilt trailer with single axle wearing 8-inch 5.70 bias tires with load rating B.  This was not good as upon weighing the trailer it came out to 1700 lbs, which exceeds the rating for B tires at that size.  Likely the saving grace was the fact that the tires, bearings, and hubs were new, tires fully inflated at all times, everything checked at every stop (hours and hundreds of miles apart, more concerned about bearing temp which was never too hot to the touch), and speed kept to 60 mph or lower.  Regardless of my luck, I immediately replaced those tires with C rated tires.  However, these now require a fairly high psi (75) to keep their max rating at 910 lbs each.  The B tires are rated for 715 lbs at 50 psi.

In retrospect, I was too fixated on replacing the original parts with exactly the same thing, without considering the future.  I replaced the hubs with another set of 4-lugs, which then limits some of the available tire/wheel combinations that are available.  5-lug hubs seem to be more widely used, especially once you go over 10-inch wheels.

I am planning to again make the move to new hubs and wheels, likely 12-13 inch range depending on travel plans.  12 inches seems to be the smallest radials that I have located readily, and for long trips that seems like the way to go...  However, bias tires may be the compromise that ends up making the economical sense (a paradox for things boat related, I know).

Your final thought was about making launch and retrieval easier.  Besides wheel diameter, the tire diameter changes depending upon the section width, meaning that the same 12-inch wheels could be 20.7" in diameter for a 4.80-12 or 21.9" for a 5.30-12.  Not a lot, but you said you were counting inches.

Based on my experience over the last season at different locations, other factors you may want to consider are trailer extensions which allow you to get the boat deeper without the tow vehicle getting as wet, lowering the rear of the bunks to allow easier "sliding," a plank instead of keel rollers, practice with the tilt mechanism (I still have trouble with this), and ramp choice (there are two lanes at my launch point, and their steepness varies depending on reservoir height...  Low lake, I go left, deep lake, right lane works better).

-Justin

[JBC]

I use 8" tires, at 910 lbs each.  Hauled my 16 from TX to CO with no problems.  I do have problems at some ramps though, even with the 8" tires, when using my Volvo wagon Cross Country.  Practically launch the rear of the car while launching the boat...get water in the spare tire well sometimes, which I can release by pulling a rubber plug I found in the pan, when I can remember to do so. While I considered modifying the trailer with an extension, I discovered I could add a hitch extension (about 12").  I have one of those hitches that can slip in and out, held in place by a pin.  Adding another foot to this set up is easy enough for launching purposes (only!), and it keeps the rear of my wagon out of the water on most ramps now.  The hitch extension slips into the original receiver, between that and the original shaft with the ball.

I thought about 12' tires for travel purposes, but with my current vehicle, simply decided a larger wheel/tire would only add to the launch problem. 

BTW, I've also noticed that different brands of the same tire/size can vary by over an inch in diameter, which is a lot on an 8" tire!

Jett 

[skip1930]

" Next time you're landing in a jumbo jet, just think of the huge weight upon contact with the tarmac and the landing speed about 160 knots or so! "

Actually the most ware on aeroplane tieres occurs not at landing with great speed but rather going slowly and turning, it's the turning that scrubs off the thread.
I fellow at the aeroport I work at had six tires replaced on his twin engine 8 passenger jet for a mear $14,700. That's high dollar rubber!

Everyone tells me my e~mail was 'hacked' Bossman said change pass word. Hope that is all it takes.

skip.

[MKBLK]

I use 8" tires, at 910 lbs each.  Hauled my 16 from TX to CO with no problems.  I do have problems at some ramps though, even with the 8" tires, when using my Volvo wagon Cross Country.  Practically launch the rear of the car while launching the boat...get water in the spare tire well sometimes, which I can release by pulling a rubber plug I found in the pan, when I can remember to do so. While I considered modifying the trailer with an extension, I discovered I could add a hitch extension (about 12").  I have one of those hitches that can slip in and out, held in place by a pin.  Adding another foot to this set up is easy enough for launching purposes (only!), and it keeps the rear of my wagon out of the water on most ramps now.  The hitch extension slips into the original receiver, between that and the original shaft with the ball.

Ah, another Volvo wagon. What are you waiting for Bob23? Seriously, where are 12" extensions available? That's a terrific solution. I really don't like dunking my Volvos tush in the drink. I try to stop just as the exhaust starts blowing bubbles, no deeper! Also, having the rear wheels go swimming can't be good for the "hand brake" which are just little drum brakes inside the hub.

Skip - just trying to be funny about the jumbo jet landing... I don't know anything about flying!

Marty K.


Jett  
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