Best handling with Tyre Size 155/65,165/65

I drove WagonR 80K KMS.I changed only rear suspension front bushes and Clutcb plate which is imp to change at 40k.Car is best in city no challenge. But for stability get 155/65 tyre profile for making height 2 inch smaller and get Shell fuel only. If possible get 165/65 Tyres then it becomes Small SUV.Else it is risky to cross 100 on 145 size tyres. Zero(10k) maintenance in 8 years.