A: The only good reason to buy only one tyre is a tyre replacement due to an accident or road hazard damage, otherwise a full set of four tyres are good. When buying replacement tyres should look and the same specifications, model, brand and tread design. Application-season tyres replace all-season tyres. Replace the snow tyre snow tyres. Replacing H speed grade tyre H speed grade tyres. This way, you will enjoy a pleasant driving experience safer.