Tyre upsizing is undoubtedly one of the most frequently asked questions from car owners. The reason behind that is simple – a majority of factory-fitted tyres on cars, especially mass-market products, are compromised in a way or two. Why? Well, it is near impossible to engineer a single tyre that offers excellent drive and handling performance, delivers smooth and comfortable ride, improves fuel economy and is cheap to replace as well. As a consequence, car manufacturers find the right balance of these properties, mix and shake all the tyre ingredients in a melting pot and come with the best possible outcome in shape of a ‘stock’ tyre.
However, while some might find the performance of factory-fitted tyres satisfactory (that’s alright!), others will always have the urge to replace these ‘stock’ tyres, depending on their respective driving styles/road-conditions, making a strong case for tyre upsizing.
Before you opt for bigger tyres though, there are a few points that you must always keep in mind. Upsizing a tyre is important but upsizing to the correct size is a must. One of the biggest blunders car owners knowingly or unknowingly commit is to opt for wrong upsize options for their vehicles. So, what happens when you put a wrong set of tyres on your vehicle? Well, the whole process of tyre ‘upsizing’ backfires and robs the vehicle of its ride quality, fuel economy, suspension composure, dynamics etc.
There are a few fundamental tips that you need to keep in mind before using an upsized tyre. First and foremost, the upsized tyre and wheel’s combined rolling radius should never exceed 3 per cent of the original or stock value. This means you have a margin of plus/minus 3 per cent to play with. Opting for a tyre over or under this tolerance is strictly not allowed as besides affecting the vehicle’s performance, it will also compromise on safety. (Also read: Basic tips on alloy wheels and tyre upsizing)
Another important aspect of upsizing is ‘Plus Sizing’. It can be summed up as Plus Zero, Plus One and Plus Two. What do they mean? Here are the answers:
Plus Zero- When the original factory wheel diameter is not altered but the tyre with larger section-width and lower profile than stock tyre is used.
Plus One- The wheel diameter is increased by one inch and the tyre aspect-ratio is reduced by one step. This maintains the overall diameter of the wheel and tyre close to the factory specifications.
Plus two- Two inches larger diameter wheel is utilized with two-step lowered sidewall profile to maintain the overall diameter of the wheel close to the factory specifications.
Based on the above formulae, we have listed down upsizing options for some of the most popular cars sold in the country: