Re: "PERFECT" Tyre Upsize for Alto Vxi I would say a No for Alto.
Reasons
There is no 155 in 12 inch that covers the circumference within 2%
A possible K10 tyre size 155/65/R13 will be only choice. That will reduce your side wall height resulting in bumpier rides and lesser comfort.
So 145/80 R12 will still provide you best results in all aspects |