Modifications and Upsizing Tyres

Upsizing the size of a tyre is increasingly becoming an obsession with people to create an added visual appeal to their car. Don’t be fooled however as shops in the aftermarket might fit your car with big wheels and tyres to make the maximum amount of money for themselves. Manufacturers offer a standard size of tyre and wheel rim on a car for a reason. They do so to give the car the best of both worlds of increasing performance dynamics of a car, increase fuel efficiency of the car offer a more comfortable ride and decrease road noise. They choose the best compromise.

Manufacturers though, do leave room in the wheel well for a calculated upsizing of tyres and wheels on their cars. This is done so that owners can upsize the tyre and wheel size to increase performance and or increase traction on different road conditions. The ideal maximum calculated upgrade that can be done without upsetting the cars driving dynamics is around 3% plus or minus of the diameter of the original tyre. Any upgrade above this will result in a noticeable drop in fuel efficiency and compromise on ride and handling of the car. Too big an upgrade in wheel and tyre size will also increase the weight of the car giving the driver no real benefit from the upgrade.

It is advisable to go for an upgrade anywhere between the 3% margin for better performance and handling, increased grip and creating a visual appeal. Do take note that upsizing the wheels and tyres may decrease the fuel efficiency of the car and may result in speedometer error on the car, if upsizing is not correct.

Some things to remember after upsizing your tyres are as follows. After the new wheels are fit onto the car, turn the steering from lock to lock positions in both left and right directions to make sure that the wheels turn till the steering wheel can turn no more. Ensure that the wheels do not touch the inside of the wheel as well, since this will damage both the tyres and the suspension and will adversely affect the handling of the car. Another check that has to be performed after upsizing is to check that there is enough space between the tyre and the wheel well to absorb bumps and potholes on the road. Take the car for a drive on an uneven or broken road to test that the bigger wheels and tyres are compromising on the ride quality. Also roll down the windows and drive and make sure that there is no noise and feel of the tyres coming in contact with the wheel wells. 

Low Profile Tyres:

Sports cars, in general, are low slung speed machines with tyres that stick close to the wheel rims. These tyres with such short sidewalls are called low profile tyres. The shorter and stiffer sidewalls of low profile tyres allow better steering responsiveness and improve a vehicle’s handling characteristics. At the same time, sports cars are capable of high speeds which mean they require more grip from the tyres to stay on the road, which is why low profile tyres have wide contact patches by default.

Low profile tyres serve a dual purpose of improving drive dynamics and providing superior grip. This is why these tyres are a common product in the aftermarket modifications sector. Wider and taller wheel rims shod with low profile tyres can be fit onto any car. However, bear in mind that all vehicles come with a 3 percent margin for increasing the size of Diameter of tyres fitted to it. Any bigger and it will adversely affect the vehicle’s drive dynamics and ride and handling.

Low profile tyres have their drawbacks though. Low profile tyres with stiffer sidewalls have less air in them resulting in a bumpier ride. Low-profile tyres being used on smooth tarmac gives an excellent feel but if venture on Indian highways with very low profile tyres, you're a potential puncture customer with a damaged tyre and the rim.

Alloy Wheels

Alloy wheels are made up of lighter and harder metals like magnesium or aluminum, or a mix of both, making them more durable as well. In a number of top-end variants of hatchbacks and executive sedans, alloy wheels come as a part of the package. Sometimes, made out of magnesium instead of aluminum, and also called ‘Mag’ wheels, they serve the same purpose as an alloy made out of aluminum would.

The upside of an alloy rim being harder and lighter improves the fuel efficiency of the car and gobbles up the nasty bumps a whole lot easier. A steel rim would bend if it hits too hard in a pit. Getting the rim straightened so that it does not deform the tyre and can handle a tubeless tyre is surely a waste of time, energy and money. 

A few things that you should keep in mind while buying an alloy wheel in the aftermarket are:

1. Know your car:

Don’t just walk into any shop that deals with alloys. Understanding your car’s dynamics before buying an alloy is very important. Consult your mechanic if you know less about the right set of alloys for your car. While at it, also see what would best fit your tyre than going in for a wider alloy and not changing the tyre. A wider alloy and a thinner tyre would compromise on handling at corners and even may not take the stress the alloy would have to transfer to the tyre.

2. Know your alloy:

Always do a bit of research on alloy wheels before buying a set. Look up information on the internet and talk to experienced people before you go ahead to buy one. Whether a set of four or a set of five would be best for your car, what brand to go for and if the alloy wheels would not compromise on handling or ride.

While buying aftermarket wheels, following are the key points to take care:

a.     Rim diameter: It is impossible to fit a tyre with different rim dia. So first thing to match is Tyre dia should be same as rim dia.

b.     Rim width: As per tyre standards, there are “Recommended” rim widths and “Permissible” rim widths for each tyre based on tyre section width. Never go beyond the permissible rim widths. This can be checked through Tyre company representatives.

c.      Offset: Offset less positive than the OE fitted wheel “Pushes” the tyre away from the car. Less positive or negative offset may make the tyre touch wheel well or fender and damage tyres. Other effects will be the alignment setting and extra pressure on vehicle geometry, turning radius.

d.     Flange profile: Usually the alloys are available in J or JJ profile, hardly making any difference in tyre performance.

e.     PCD, no of holes: These have to be confirmed, should be same otherwise fitting the alloys on hub is difficult. In some cases, customers fit wheels with “Similar” PCD (For example 100.4 PCD wheel instead of 100PCD). This results in vibration in the vehicle.

f.      Never buy multi-PCD wheels: Wheel manufacturers often build wheels than can match two sets of PCDs on two sets of vehicles. For example, older Maruti-Suzuki cars used to come fitted with 114.3mm PCD section wheels (with four holes) while the newer ones come with a 100mm PCD section wheel (also with four holes). As far as possible avoid these as they have less material than standard PCD wheels due to more holes drilled into the centre section. Less metal can lead to wheel failure due to more stress on a lesser cross section of metal.

g.     Don’t put and forget: A little maintenance like wheel alignment, wheel balancing and tyre rotation, just like it would be required for a rim is as important for an alloy as well. Usually, in alloy wheels, wheel weights are stuck on and not clamped on as they would in a steel wheel.

Also, the common roadside “Chisel and Hammer” puncture wallahs can make dents or chips on your expensive alloys, deteriorating their looks. Try to open and fit tyres only at shops with quality “Tyre Changers”