
Note that I'm driving a 2001 Nissan Patrol 4500 automatic. When I bought the truck, I had 265/70r16 General Grabber A/T's on but alas they had worn a bit much...
For the last week I had borrowed some Kumho AT51 Road Ventures (285/75r16) to see how the gearing on the automatic would handle the bigger tire size. Turns out not much of an issue, I did notice some "searching" around 100km/h, when going uphill. This was rectified by putting foot around the 90's or just dealing with less power for a little while. If I had a trailer/caravan/boat I'd stick with the 265/75's on the automatic, fortunately? not an issue for me.
I got it done at Tyremart Autowiel Centurion West, the guys are awesome there, great service. Pics below


Part of the reason for driving the bigger Kumho's were also to check the fuel consumption on a bigger tire. So I had General Grabber AT 265/70's and tested using the Kumho 285/75's AT. My calculations for consumption on the bigger tire is below, unfortunately I did not really pay attention to consumption when I was on the General Grabbber (was having to much fun owning a patrol

The first thing I did was check the tyre size comparison, so I could work out the differnce in km since the Kumho's were bigger than the OEM size. I used the following site https://tiresize.com/comparison/. Comparison below:

Basically this meant that I'm going to see 7.2% less distance on the odometer, because of the 7.2% increase in circumference.
302km (50% town %50 highway
62L used (I tried to behave, so not to much of a heavy foot)
=4.87km
0.072 * 302 = 21.744
302+21.744 real total distance traveled
= 323.744 / 62L = 5.22km/L
I know its a small distance to be working out on, but its a decent estimate. Next up will be seeing how consumption differs between the previous AT and current MT since they are both the same size.