hey anyone know what the largest size rim you can put on a BA XT is?

22 rear 20 front i belive

I believe 19" would be the most?. I could be wrong and I am sure someone will say that.

1. Tyre Overall Diameter

a) New South Wales/ACT, Victoria, Northern Territory, South Australia
The outside diameter of the wheel and tyre combination must be no more than 15mm over the largest diameter wheel and tyre combination as specified for the vehicle and not more than 15mm below the smallest diameter wheel and tyre combination specified for the vehicle. Speedometer accuracy must be maintained for the selected tyre and wheel combination.

2. Change to Wheels

a) New South Wales
Wheels up to 26mm wider than the largest optional wheel recommend by the vehicle manufacturer for the vehicle can be fitted without the need to notify the RTA (Road Traffic Authority)

3. Wheel track variation

a) New South Wales/ACT
Passenger vehicle - the wheel track must not be increased by more than 25mm beyond the maximum specified by the vehicle manufacturer for that particular model.

cmon hes 16, hes gonna break every rule and law he can. but yes i think its 2inch either way max of upsizing or downsizing.

Because Zacbaxt is 16 doesn't mean he WILL break rules and he was asking a valid question and I gave him a valid answer.

Noooope.
Law is 15mm total size, so you can run 20s with low profile and its still legal.

thanks guys. thats great