@njcustom can you please pm me the details for how to buy the screws conversion kit I read about on here somewhere? Thankyou, Andy

The size is the same as the Vega 11.5 x 6.5 - 6. I don't know the compound. I only had a choice of the one tire so couldn't be too fussy about compound. It is marked D20A if that helps. I did fit it with the specified rotation, seemed like the right choice. For anyone wanting to do the change themselves my experience was that removing the wheel assembly was the easy part. I couldn't even get the tire to budge so took it to my local tire guys who used a machine to break the bead then tire spoons to remove and refit the tire. They then used air pressure to reseal the bead. It seemed to take a lot of air pressure to snap the bead back into place so I don't think you could achieve that with a hand pump. It was a bit scary trusting my Onewheel to them but luckily it seems to have worked out well. Given I'm in Australia, sending it back to the US for servicing would have cost at least $500 in shipping and probably taken 3-4 weeks so doing it myself locally was the only real option.

So for those interested here is the final result! Needless to say I'm pretty happy. Two days off the road is two days too long.
I road the new tire into work today and loved it. It's hard to say whether the Hoosier is much different to the Vega as my old tire was very worn and the Hoosier is so sticky and new. I do like how it looks though!

I have a new approach. As far as I can tell looking at the chassy the braided cable is on the left hand side. I should be able to use that orientation to fit the tire. Thankyou to all for your suggestions and help. I will post pictures of the mission once complete.

Found a photo online. It showed the valve on the left hand side (from behind). It would be good if someone could confirm this though.

I picked up the Hoosier tire and it has a directional arrow. I left the rim at the local tire shop and need to make sure it gets put on tight.

Guys I need a quick answer. Which side of the onewheel is the valve on?

@CABALLERO great tip! I found a Hoosier dealer locally and should have the tire within the week.

So the latest update on the tire situation is that apparently this size 11.6 x 6.5 - 6 is not authorised for use on go karts in Australia. I am being offered numerous different sizes but nothing that meets the Vega specs so it looks like I'll be importing something from the US. I have sent a request for international shipping to ts racing and am seriously hoping they come to the party.

For those interested her's a pic of the current wear with slime oozing though!