My motorhome is 6 or so ton .90lb is the recommended tyre pressures . Have run 70 lb in duel rears . Keep max speed over distance to 85 / 90 kph . Checking tyres heat every now and then .The vibration is there at near ANY speed in outback tar roads . 91.5 / 225 tyres The rear spring rates in my case could be a little hard for these conditions . After all the suspension is designed to carry 12 ton as a truck . Could be the same in your case ? Ours rides better with full water tanks etc .
The heavy trucks and hot weather causes this . Coil spring vehicles seem to travel better. Not to say caravans are doing ok though . Depends on vehicles suspension. Ours at present is too firm ! Mind you real truck tyres with full on tyre pressure doesnât help !!
Trouble is most the roads up north WA / NT have them . Not just gravel or dirt roads ..
This just goes to show how things must have changed since I was last up that way.
We had no such experience in 2000 to 2008.
Sure there were patches that were a bit wavy but never any corrugations on sealed roads.
Cupie - the Bruce Highway in Queensland has corrugated sections near Calliope and also near Rockhampton. Both are just before new roadworks and roundabouts - so I figured it must be from braking, as it is coming into the roundabout or out of it. Weird, eh?
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jules "Love is good for the human being!!" (Ben, aged 10)
With my MH i do a fair amount of dirt roads each year ... certainly over 5,000 depending on where I am
I have a simple attitude to dirt roads & corrugations -
a) drop tyre pressures by 1/3 .... in my case from 60 psi to 40 ~ 45 psi, and
b) drop speed also by 1/3 .... meaning I cruise at about 60km/h for much of the time
Not had any tyres blow out or other issues
Once back on the good roads, it's max of 80km/h until I can pump up the tyres at the next town's servo
NB: because so many vehicles start at very differing tyre pressures, quoting 'PSI numbers to reduce presure by' does not make much sense. It is the proportional reduction in pressure that you need to find about
Apparently the air suspension on trucks make it worse on the Black top also . Compared to old leaf springed vehicles . Just came down Stuart H Way to Victor Harbour. Some sections on the Stuart have it too . Yep same here I drop tyre pressures close to 40% lower on rear duel wheels on gravel or more the point outback dirt roads . Sometimes its just the soft sand rolling infront of tyres then tyre climbs over . Like a wave every meter or so ? As it often happens on SMOOTH dirt roads . Often changing speed ? Faster or slower helps ??
-- Edited by Aus-Kiwi on Wednesday 2nd of May 2018 08:11:10 PM
Thanks for the replies guys.... Where I like to go is isolated, Like to camp close to the beach and most roads are rough.. I traveled between 15-30ks and hour on these roads, but some are very bad.. I have a decent on board compressor.. I will lower the pressures by 20-30% and keep the speed slow.. The missus doesnt like the rough ride and the beers dont like it either.....
My next adventure is on a dirt road thats 35ks to my destination... going to be fun...
Ill play with pressures and post my results.. Thanks again for posting.. Mike
pic is an isolated spot on the YP SA... very rough road.. took 1 hour to do 27ks....
I've just returned from a week in the High Country of Victoria in my 4WD and roof-top tent - frequently my speed over the tracks averaged around 12kph. Take your time.
I have a mantra on these rough tracks: "I don't want to get there quickly... I just want to get there" :)
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"I beseech you in the bowels of Christ think it possible you may be mistaken"
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