I do have a pretty Big Rig, my Dodge Cummins Diesel is really loaded.. Like in the back, a fridge freezer, a bed slide out, big tool box, smaller Sidchrome 10 drawer tool box, and a 230 litre auto shut off fuel bowser... Hmmm, I just like to travel heavy I guess..
Now my 21' Bushtracker is one of the heaviest ever built. It has the Air Suspension with tank for tyres and air tools (up 60 kg), fibreglass exterior (up 60 kg), a new 7.5 kg washing machine that turns into a 4 kg dryer we want to trial (up 60 kg), an Electric start 3 kva Honda EU3.0is that we wanted to see if it would run TWO Truma Aventa II air units (up 69 kg and yes it does), two roll out slides outs on a big box, for the new gas bottle easy access, (up 20 kg), two 200 AH Lithium set ups (extra 20 kg), 6 solar panels up two from the normal 3-4 (say up 30 kg), big Stainless Marine style fridge with 70 kg roll out freezer (25 kg?), power step, and about every option we are thinking about and playing with...
So, my Bushtracker has a ball weight over 400 kg. And my 2500 Dodge Cummins Diesel Ram has air bags inside the coils so it is really like a 3500... The point of all of this?
REAR TYRES, THIS IS NOT A DUALLY, NOT A DRW, AN SRW (Single Rear Wheel)... My 20" American truck tyres are rated at 1650 kg. So I took it to a weigh bridge..
What you do is pull on the weigh bridge:
With just your front tyres of the tow vehicle off the wb. Get a weight. Then go forward until your rear tyres are just off the wb.. Get a weight. Fist weight minus the second weight, gives you the loading on your rear tyres. Now my tyres are about the biggest Load Rating in the Industry at 1650 kg, that equates to 3300 kg for the two of them. I am so loaded up, the van and truck (full water tanks) weighed 6.20 Tons, and off the scale my van weighted 3.62 tons (heavy 21', about the heaviest), so the difference is 2.68 tons on the rear wheels..
Now that is OK, but when I got back I looked and I was about 50 kg off a full tank in the truck at say 50% between front and rear tyres, so +25kg.. And my big tank was down about 120 litres, at about 70% back from the front wheels so add (say 80 kg) if full. And my jerry cans in the front of the Bushtracker were not full, so OK, at 80% the distance from the suspension to ball, (add 35 kg max)... In total add on about 140 kg if totally full, brings me up to 2.82 so I am a good 15% or so below the Rated Maximum Load, (which is also at the maximum tyre pressure in this case 80 psi..).
The problem is that this is a 20" truck tyre. Most of you would not have that high of load rating. In bigger vans, vehicles loaded up or with boats on top, so that weigh bridge test and see what the actual load rating is on your rear tyres OK?
In my case, if I got much higher, I would need to get a Dual Rear Wheel Dodge, a DRW. Right now I am in the top end of an SRW category, and for safety I would rather be in the bottom end of a DRW category OK?
This test is particularly important to smaller tow vehicles, look at your load rating, and it is worthless unless you have that maximum tyre pressure (cold) to achieve it. Worth checking out..
Keep in mind, against popular belief, on a heavily loaded vehicle a rear tyre blow out is far worse that a front tyre blow out... You can counter steer a front tyre blow out from something like a rock bruise, but a rear tyre blow out can slew you over to the side pretty significantly...
On the Road, Ranger....