Can I adjust the down shift points, I have about 5% bigger tires I realise this can screw things a bit, e.g. when your going 100 kph, trans thinks it's 95 kph (1 kph = .6214 mph). Down shifts 5>4 to easy at part throttle + about 117 kph (73 mph) at WOT. No down shifting above 110 kph (100% throttle) would be nice, + less sensitive at part throttle.
Table D5038 is set to 100 kph
Table D5008 is part throttle
Would lowering the values in these tables help?

Ed, altering those tables is what you need.
If you want the drop from 5th to 4th to occur later then figure out the speed where you want this to happen and increase the throttle percentage needed. You will notice a change as small as 5% for sure.

Cheers,
Ross

One other thing you might look at. Shifting is affected by the throttle base table. If you altered that table or altered the fuel table in part throttle areas, shifting is often affected, mostly to the worse. In other words, if the engine is being "fooled" into applying more power, the trans isn't being told. By either adjusting the throttle base table in the shifting problem areas, or leaving those problem areas alone in the fueling area, shifting often improves.

Thanks guys, lowering D5038 by the required % works, e.g. 117kph x 8% =107.6kph so I set it from 100 - 8% to 92.
Also lowered the last 4 boxes in D5008 by 5%.
In this table the % steps seem set + you adjust speed or did I miss something.