165 is the tyre width in millimetres, 45 is the sidewall height as a percentage of the width, R means radial construction, and 15 is the wheel diameter in inches. You will also need to match the load index and speed rating shown after the size on the sidewall.
It will only fit a 15 inch rim, and the wheel width needs to be compatible with 165/45 R15. Many tyre makers approve this size for rims around 5.0J to 6.0J, but you should confirm the exact range for the tyre you choose and check clearance to arches and suspension on your vehicle.
Use the tyre placard (often on the door shut) or your handbook to find the required load index and speed rating, then match them when selecting 165/45 R15. You will often see ratings like 72V in this size, but the correct choice is always the one specified for your car, or a higher load rating if approved.
Yes, but 165/45 R15 can have fewer pattern options than more common sizes, so availability varies by brand. If you drive mostly in mild UK conditions, an all-season tyre with 3PMSF marking can be a strong year-round option, while dedicated winter tyres suit regular cold, wet and icy roads.
The 45 profile has a short sidewall, which flexes less than taller profiles and can transmit more of the road surface into the cabin. Keeping 165/45 R15 inflated to the correct pressure and maintaining wheel alignment helps reduce harshness and protects the rim and tyre from impact damage.