Maybe something you don't want to hear, but it sounds like you settled on the Alto with an idea of upgrading soon-ish?
If that's the case, maybe you want to reconsider if you want to spend on non-essential add ons. Investments like these rarely adds to the recovery at the point of sale.
But if you still want to go ahead, pull one of the wheels out (maybe your spare doesn't have the same markings as the other wheels) and find the offset. You may even be able to find it if you google.
Then, figure out which wheels you want to go for and get the offset, diameter and width of those wheels.
Feed those into the site below and it will say exactly how much the wheel will move within the wheel well and you should be able to figure out any clearance issues.
https://www.willtheyfit.com/