275 is the tyre width in millimetres, 35 is the sidewall height as a percentage of the width, and R18 means it fits an 18 inch wheel. This size is typically suited to wider rims (often around 9.5 to 11 inches), but the correct wheel width depends on your exact wheel and vehicle specification. Check the wheel markings, your handbook, or the tyre placard, and match the required load index and speed rating before ordering.
Sometimes, but it is not a like-for-like change. Moving to 275 width can affect clearance to suspension and wheel arches, and it usually requires a suitably wide rim to avoid poor sidewall shape. Even when the rolling diameter looks close, handling balance and tramlining can change, especially on staggered setups. Confirm the approved sizes for your car and wheels, then choose a tyre that matches the original load index and speed rating.
Follow the ratings listed on your current tyre sidewall or your vehicle placard and match them exactly, or choose higher, never lower. Many 275/35 R18 fitments use higher performance speed ratings (such as W or Y) and may be XL (reinforced) to support heavier axle loads on powerful cars. If you are unsure, check the manufacturer specification for your exact model and trim before you buy.
Yes, 275/35 R18 run-flat tyres are available from selected manufacturers, but they are best used when your car is designed for run-flats and has the correct support system (such as TPMS and the manufacturer-recommended suspension setup). Run-flats can feel firmer and may transmit more road noise on UK surfaces. If you switch from run-flat to standard tyres, plan how you will handle a puncture, such as carrying a mobility kit where appropriate.
Choose based on the temperatures and conditions you drive in most. Summer tyres suit milder months and deliver the sharpest dry and wet performance in warmer conditions, while winter tyres improve grip and braking when temperatures regularly drop below about 7°C. All-season tyres balance both for year-round use, but can feel less precise than a dedicated ultra high performance summer tyre. For stability, keep the same tyre type across an axle and replace in pairs where possible.
