I've got 2 tyre placards, can I use both at once?

Hi everyone

I've got an 80 series. I don't know about other 80 series cruisers, but my one has got 2 placards on the drivers door.

One's for 7.50 16's and one is for 275 70 16's.

Both are slightly different diametres, very different widths and different speed ratings.

On the limits you can have on tyre sizes, speed ratings etc, lets just say I had a tyre diametre, width and speed rating that is half legal on one placard and half legal on the other placard and if you go of both put together, it's legal, can the police book me or not?

In other words, can I use one placard for what suits me best and use the other placard for what suits me best both at the same time, or can I only use one at a time?

If it depends on the state, I live in Victoria.


Thanks for your help everyone