Ranger Mods

I followed the Ford guidelines with tyre pressure when towing 38 front & 43 rear.

As the ambient temp rose from 9 to 20 I noticed the ride becoming a little harsh & noisy.

I checked the tyre pressures on OBDLink and sure enough they were well up, 41 in the front and 48 in the rear.

On my next rest stop I let them down to 38 and 43 and the ride was back to smooth again.

My question is as tyres increase pressure with heat should they be left high?

If Ford are allowing for an increase in pressure it would be impossible for them to know what that increase will be.

All tyre pressures listed on the placard or anywhere else are always measured with a cold tyre.

You are correct, they will not necessarily know the pressure but a good way to find the right pressure is to find the smallest increase in temp between cold and hot. Everyone's load is different.

When I started driving today naturally the pressures were down but after 12 klms they were up.

I would rather drive 12 klms on an under inflated tyre than 500+klms on an over inflated one.

saeb wrote: ↑Mon May 21, 2018 8:35 pm All tyre pressures listed on the placard or anywhere else are always measured with a cold tyre.

Yes, exactly so my question is do Ford want me to drive the Ranger with 38/43 when I tow with hot tyres or start with 38/43 cold and wherever they end up that's fine.

The ambient temp is fairly low so I would hate to think where pressures would end up when the bitumen hits 60 degrees.

Personally I would try 38/40 cold or find that 4 to 5 degree cold to hot difference then adjust accordingly. Too low and you are going to put even more heat into the tyre than too high. I wonder how much heat transfer there actually is from a road surface? With so much moving air as the wheel spins I would not have thought is would change too much

I usually run around 39 and see about 42 to 44 when how depending on load etc.

What is the maximum pressure on the tyre?

The only way you're going to get definite answers is to email the tyre manufacture asking the exact questions you asked here. BF were good in this regard and came back with some good information and useful figure, when I had my Land Cruiser.