Tyre Upsizing tips specially for Indian road conditions.

Upsizing your Tyre? Tips and Tricks After buying a new car, the first things that most people upgrade are the wheels and tyres. There is no doubt they add visual pizzazz to your new pride and joy. but they could also potentially damage your car. So here is what you need to know before you upsize.

IF YOUR CAR came with steel wheel rims, it does make sense to change to alloy wheels. Though alloys are dearer than steel rims they offer many advantages. SUPERIOR LOOKS Good looks are the most obvious reason for choosing alloy wheels. Big, well-designed glinting wheels can enhance the looks and appeal of your car like no other single feature. REDUCTION IN WEIGHT Unsprung weight is the combined weight of the wheel, tyre and suspension or the weight of the parts that the springs and the bulk of the car rest on. And lighter is better. Both ride and handling are considerably improved with a lighter wheel. IMPROVED FUEL EFFICIENCY This reduction in mass or the wheel also leads to an improvement in fuel economy, especially in stop-start traffic. IMPROVED BRAKING AND PERFORMANCE A reduction in the weight of the wheel also allows the forces of acceleration and braking to be transferred better. COOLER BRAKES Critical as far as India is concerned, alloy wheel designs that allow a greater airflow to the brakes, can considerably reduce brake fade and increase the life of the brakes. UPSIZE FOR AGILITY Cornering performance, especially turn-in and steering responses, also improve dramatically when wheels or rims are upsized or taller. UNDERSTAND TYRE UPSIZING Next step, getting the right sized tyre. But before you do that make sure that you understand how it works. Many aftermarket shops will try and sell you the tyre and wheel that makes them the maximum profit. If you get the size wrong, not only the ride and handling of your car suffer, but it could also damage your car. There is a method behind the madness of upsizing tyres and wheels. There is a reason that every manufacturer offers a standard size of tyre and wheel rim on a particular car. That’s because the car’s wheel and tyre sizes have been chosen to balance between the performance dynamics, fuel efficiency, ride and handling. So if you change from the standard size, one or all of these qualities will change. For example, if you go for a larger diameter wheel, you will have to put a lower profile tyre on it. A lower profile tyre gives the car a certain élan, but the lower stiffer sidewalls completely change the driving dynamics of the car. If you have completely smooth tarmac, the car will handle if you are driving on rails. But on anything less than perfectly smooth roads, the ride will be super stiff and you’ll need an appointment with a chiropractor. CHECK THE RIGHT SIZE The first thing to remember is that there is not much scope to deviate from the total diameter of the tyre that comes originally fitted in your car without making drastic changes. To calculate the total diameter of the tyre, add the diameter of the wheel rim to the size of the sidewall. Here’s how you do it. Read the marking on the side of the tyre. For example, it might read 175/70/R13. Now you know that 175 here refers to the size of the contact patch of the tyre in millimetres. The next figure 70 refers to the height of the sidewall in terms of percentage of the contact patch. R here means a radial tyre which is irrelevant for this. But the next figure 13 is the rim diameter in inches. Let’s calculate the total tyre diameter. 17.5 cm + 70% of 17.5cm + 13 X 2.54cm (1”= 2.54cm). Now do the math. For a safe upgrade, the tyre size cannot be increased by more than three percent of the car’s original total tyre diameter. Any difference of more than three percent is just not recommended. The ideal maximum calculated upsize that can be done without upsetting the car’s dynamics is around three percent of the original total tyre diameter. Any increase above this will result in a noticeable drop in fuel efficiency and compromise ride and handling. It is best to go for an upgrade within the three percent margin for better performance and handling, increased grip and creating a visual appeal. CHECK AFTER FITTING After you mount your new wheels on the car, sit behind the wheel and turn the steering from lock to lock. Turn the wheel in both directions. Check that on full lock the wheels are not touching the inside of the wheel well or any other part of the body. Also, check that there is enough space between the tyre and the wheel well to any absorb bumps or potholes on the road. Go for a drive on an uneven or broken road to test that the bigger wheels and tyres are compromising the car’s ride quality. THINGS WHICH IMPROVE The car’s aesthetics is point number one. Upsized wheels add appeal and enhance the look of your car. Wider tyre also provides more surface area for the car’s weight to be distributed on the ground, thereby increasing grip and traction. This results in a better drive and stability. THINGS TO WATCH FOR Wider tyres have their downsides that you should know about. The wider tyres with more traction might reduce the car’s top speed. Acceleration might be affected due to the increase in weight and greater traction. This will affect the vehicle’s fuel economy. If you prefer lighter steering, think twice since you’ll need to put in more steering effort. Also, remember that your speedometer and odometer will not read correctly.