Good to see the most important issue being addressed - that is avoidine wear of the heel. And tyre wear can be a significant issuer especially where it is allowed to go past its indicated maximum.

The lift chains also have to be adjusted to keep the heels off the floor with mast at 0* vertical. Check the tires for wear, replace as necessary. Check the chains for wear, again replace as necessary, this is also done with a gauge. Once these two conditions are satisfied, you can then adjust your lift chains, starting with your secondaries if you have a three stage mast. Adjust so the inner channel is just a bit higher than the intermediate channel, and run the mast right to the top and see if the stop blocks are hitting. Adjust them down as necessary. You should be in the ballpark then. Now bring the mast down, set the mast to 0* vertical, and run the primary chains up until the fork heels come off the ground, I like 10MM but some go to 1/2". Either is fine as long as the carriage stop block does not hit the mast channel stop. If you cant find a happy medium where the forks are off the ground and the blocks are not hitting, your tires are likely worn out or youre not quite vertical.

Thanks, guys.

The 2 forks used together are to match the capacity of the lift truck and the capacity of most lift trucks is based on a 24" load centre or centre of the load.
There are standard sizes (width & thickness) to meet this capacity.
I would not want to put heavier capacity forks on a lift truck, it could be sending the wrong signal to the operator.
Dragging forks on the floor/ground will cause forks to wear out. Most/all lift truck dealers have fork wear calipers to check for fork wear. This should be done once per year maximum interval. Once a fork wears more than 10%, it (usually they) have to be replaced. 10% fork wear means the forks are now only rated @ 80% of their capacity and that's the cut off.
We're not talking about fork deflection here.

What you need to be asking is what load centre you are working at. If you are working at 500mm then a 125 x 45 section fork in "industry normal" material has more than enough capacity to match your lift truck capacity. If you were to use a fork with an "optima" heel then you would have a thicker wear zone than a standard 50mm fork and then the difference between 45 and 50mm thickness is not relevant.

The 5mm isn't going to make much difference. The intention was to cater to possible small gaps in the wooden pallet skids that are delivered to us. So, we can avoid experiencing the forks being jammed in the skid.

Yes, it will wear off eventually, and that is when we need to change i.e. when 10% has worn out (as recommended by safe practices)

Your question is?

My question is, how is that 5mm going to affect you?
If you must have 45mm then you can custom order wider forks.

Heck your operators will wear off that 5mm in a matter of weeks anyway :-)