Time to defend my assumption, whilst it does actually make the corrugations worse, a higher
speed reduces the duration you feel the corrugations for and the duration of your trip, which is
why I believe that many of us out bush feel as if speed helps the situation.
Given the evidence, you clearly should slow down over the bad corrugations. 80km an hour
seems like a fair speed to travel at over corrugations for skilled drivers. You are going to have to
make a call about what speed you choose for corrugations. If you are not experienced I
recommend 60km or lower as you can really get thrown across the road through corrugations.
Tyre pressure:
I nailed this one! What I was hoping to find though, was an ideal tyre pressure, say 28PSI. I
didn’t and simply the lower you go the better it gets. I would never recommend driving at 20PSI
along these roads nor would I recommend 25PSI. The lower your tyre pressure the more
vulnerable I feel you are to creating heat in your tyre and weakening your sidewalls. As you
know I completed the test in 32 deg temperatures.
In the testing that I did at 20PSI my tyre temperature hit 49 deg. I have only seen my tyres
get that hot previously if the day is over 40 deg. I will have to turn the decision on tyre pressure
over to you. You're going to need to make a decision based on how fast you plan on travelling,
what you’re legally able to run in your tyres and what you feel is best for your car.
Now that I have completed my fence sitting I will tell you what I now run in my Prado. This is
not a recommendation to anyone it is simply what I do.
Without load:
General Speed:
90km-80km
With load:
General Speed: 85km-75km
Rear: 30 PSI
Front: 28 PSI
Tyre Pressure: By sight
If you do find the need to do your tyre pressure by sight, make sure you have a good in-car tyre
monitoring system so you can make sure all is going as per the program in each tyre.