Normally, at the BIC, we pit one car or bike against the other. This time, however, it’s the round bits of rubber at the four corners that we’re interested in. So, we have two identical Volkswagen Polos and four sets of tyres to put to the test. Read on to find out more…
What’s the one piece of technology in your car that you take completely for granted? Allow me to hazard a guess – your tyres (and I’m willing to bet on that)! I’m certain, in fact, that you’d be able to hold your own in a conversation about engine configuration, even power output, and certainly about in-car technology. But, how many of you actually know what goes into the round bits of rubber on the four corners of your car? In fact, how many of your even know what brand of tyres your car is running?
After all, these four round bits of rubber are the only contact patch between your car and the road – they’re the only parts of your car that actually meets the road, the parts that transmit all the technical wizardry in your vehicle onto the road surface. One could argue that more than any other component, it’s tyres that affect the performance, safety, and comfort of your vehicle. So, unsurprisingly, the process of making tyres is a bit of a black art.
There’s a lot to consider when making a tyre. For instance, the more rubber that meets the road the more traction, or grip, you have on a dry surface, which is why most racing tyres have no tread on them at all – referred to as slicks. In the wet, however, race cars switch to purpose built rain tyres that have grooves to channel the rain water from between the road surface and the rubber. In a road car, of course, tyre manufacturers have to find a balance between wet and dry grip, rolling resistance, treadwear and noise, amongst several other performance characteristics. The tread design also has to provide feedback from the road, while riding comfortably at the same time. Moreover, it has to be silent enough going down the road to ensure that you can actually hold a conversation in the cabin. Let us not forget that it has to be pleasing to the eyes as well, since a lot of people buy tyres these days purely for their tread pattern.
In today’s environment, tyre manufacturing also has to be eco-friendly, while the tyres themselves have to be light enough to reduce unsprung weight and aid fuel efficiency. In fact, many tyres even consist of compounds such as silica to enhance fuel efficiency and wet grip. Plus, they have to be durable, and safe at speeds well in excess of 200km/h.
Let’s just say that a lot goes into making these innocuous pieces of rubber on the four corners of your car. So the next time you get into the drivers’ seat, spare a thought for the rubber that meets the road.
What we have here are a set of tyres each from Apollo, Goodyear, JK Tyre, and MRF. The plan is to mount them on identical cars and gather some data while lapping the BIC. Our aim with our inaugural tyre test is to get you thinking about the importance of the tyres on your car. So, read on…
The choice of car for this test was crucial. We wanted a car that was mainstream, yet performance oriented to really put these tyres through their paces. Since we wanted to test mainstream tyres on a regular car, and small cars make up 70% of the market, it had to be a hatch. That being the case, the choice was an obvious one. The only driver-oriented small car in our market – save for the much more expensive BMW 1 Series and Mercedes-Benz A-Class – is the Volkswagen Polo GT TSI. The Polo Cup, seemingly, has enabled Volkswagen to create a sporty enough image for this Teutonic hatch – and so a GT version of the Polo had many takers when the TSI was launched last year. It has a great chassis for starters, and it’s powered by a 1.2 litre turbocharged four-cylinder petrol engine putting out just over 100 horsepower via a highly sophisticated 7-speed dual-clutch gearbox. Having driven the Polo Cup car many times, we knew just how much potential the Polo chassis has. In GT TSI trim, it has a reasonable amount of poke, and the 7-speed DSG means that we don’t have to fiddle with the gear lever – I could simply slot it in ‘S,’ and let the extremely responsive gearbox do the rest – thereby providing us with the most consistent lap-times. Needless to say, we’ve done hundreds of laps around the BIC – so consistency was never going to be a problem, but just to be sure.
Volkswagen was kind enough to loan us two identical TSI’s for the test, which made our lives a little easier. However, we only used one car on the day of the actual test to ensure that the only performance differences came from the tyres and nothing else. Both cars were, however, used to run in the tyres on the road prior to the test.
The advantage of the Polo is that it’s very much a point-and-shoot machine, so we didn’t really have to muscle the car around the track. In the future, however, I would prefer to choose a slightly more powerful car for a test such as this to really test traction, and the ability to control wheelspin, coming out a corner. Moreover, one of the tests we had planned was an acceleration test to gauge traction off the line, but the Polo’s electronics didn’t allow us to launch from a standstill! Nevertheless, the Polo did its job at an ambient temperature of 45 degrees Celsius, and a track temperature of 65 degrees Celsius. So, it wasn’t just the tyres that were being put to the test.
The BIC is a track that we’re exceedingly familiar with, as we’ve done hundreds of laps around here. Over the years, we’ve gathered a huge amount of data while testing over 50 cars and bikes at the track. Its 5.1 kilometres consist of long straights, fast chicanes, elevation changes, decreasing radius corners, blind approaches, and, most importantly for tyre testing, long corners that are punishing on tyres. We’ve tested many-a-car here where the left front especially – being a clockwise circuit – takes heavy abuse and begins to show signs of wear after just a couple of laps. And, fortunately for us, the BIC has a garage with state-of-the-art tyre changing equipment – which meant that this test was a go once we could get our hands on a couple of sets of tyres. Every time I visit the BIC, in fact, I can’t help but think that it’s a phenomenal facility – a jewel in our crown if I can be so bold.
Yes, this is very much a performance test, but it’s not a test exclusively of extreme performance rubber that’s meant purely for the track. The idea behind this test is to get regular tyres that you and I buy for our road cars and gauge the performance differences to get a better appreciation of the work done by the tyres meeting the road.
So, the four brands that we have are Apollo, Goodyear, JK Tyre, and MRF, and the tyre sizes are identical – 195/60 R15.
The testing procedure was quite straightforward. The tyres were all run in on the road prior to the test. On the day of the test themselves, they certainly didn’t need to be warmed up as the track temperature was in excess of 60 degrees Celsius.
Prior to testing, the pressures were all set to 30psi. We then started off by doing a sound test. The Polo was brought up to a steady speed of 120km/h in top gear on the 1.2 kilometre back straight, and the sound level was measured using a decibel metre.
The next test was braking from 100km/h to a standstill. A 100km/h target speed was fed into our GPS enabled VBOX, which beeped when the ton was achieved, and this was followed by full braking until the car came to a complete halt. The resulting stopping distance was then measured using said VBOX.
Next was a timed lap around the full length of the circuit to test handling, grip, and overall performance. Again, lap time and telemetry was measured using the VBOX.
The final test involved just a weighing scale and one example of each tyre, which was weighed for the simple reason that ‘lighter is better.’ You see, tyres form a crucial part of the unsprung weight of a vehicle – i.e. that portion of the vehicle that’s not supported by the springs in the suspension. Unsprung weight is crucial to the ride and handling of your vehicle. Lower unsprung weight improves both because it enables the suspension to react quicker and perform better in keeping the tyres in contact with the road surface.
One test that we were unable to include in the first edition of this tyre test was wet braking – simply because we had our hands full with all of the above. The idea was to create a simple test that was easy to execute and understand for the first time. As we go along, we’ll continue to gather more data and conduct more elaborate tests in future.
The tyre that performed the best in each of the four parameters – sound, braking, lap times and weight – were awarded 100 points. The others were awarded points based on a percentage of their relative performance. This was added up in the end, with a weighted average in favour of the lap times, since this is a performance test after all. Still with me? Good, to the tests then…
Tyre noise is an element that’s largely ignored by consumers, but tyre manufacturers go to great lengths to ensure that their tyres are silent. Tyre noise, in fact, can be quite intrusive on the highway, and so this is quite an important parameter to consider.
As explained before, the sound of each set of tyres was measured at a steady speed of 120km/h in top gear on the back straight. This was done in both directions, and the results were averaged. It has to be said that the results are fairly similar for all the tyres. The MRF’s are the loudest by a small margin because they seem to have the chunkiest tread blocks, especially on the shoulders of the tyres. If you look at a set of knobby off-road tyres, for instance, they tend to be quite loud going down the road. The MRF’s are, by no means, that loud – but their fairly aggressive tread pattern probably explains the highest dB rating. The MRF’s do have the nicest looking tread of the lot though, if that’s any consolation.
Braking, of course, is crucial. And all the tyres performed pretty well it has to be said. The test itself was easy enough to perform. Accelerate to 100km/h and then stand on the brake pedal, allow the ABS to engage, and then wait for the car to come to a complete stop. Repeat the test in the opposite direction and average the results.
The difference in braking distances between the MRF ZLO’s and the Goodyear Assurance was just 3.1 metres. However, if you consider the fact that 10 feet in an emergency stop could make the difference between having an accident and avoiding one, it’s a crucial test. A more telling test would be wet braking, which we’ll conduct in the next edition of our tyre test. In this case, it would appear that the softer sidewalls of the MRF tyres help it during the weight transfer under braking to increase the contact patch with the track and reduce stopping distances. This same trait may hurt the performance of the tyre around a full lap of the BIC – which it does as there’s too much squirm between the tread blocks – but it helps in an emergency brake test. Accident avoidance by braking and swerving may be a different story altogether though.
As explained before, unsprung weight is crucial to the performance of a vehicle, and so the tyres that are the lightest of the lot – everything else being equal – should perform the best. Again, the emphasis here is no performance, and we haven’t tested the wear rate or durability levels of any of the tyres.
This is the most important element in our test. When the results are tallied, this component of the test contributes to 50% of the final test result. A full lap of the BIC is the best test, after all, to gauge grip, handling and feedback from each set of tyres.
Both the Apollo’s and the Goodyear’s have a fairly uniform central rib that enables them to provide the best feedback through the steering. They feel far more responsive on the turn-in compared with the JK’s or the MRF’s. The flip side of that is the JK’s, for instance, seem to ride the kerbs far better than any of the other tyres – which suggests that their on-road ride could well be the best of the lot. But we’re not testing ride quality. We’re here simply to look at performance, and it’s clear that the Apollo’s and Goodyear’s are able to turn-in better and carry more speed through the corners – as evidenced by the fact that their top speed at the end of the back straight (159km/h) is higher than the JK’s (156km/h) and MRF’s (155km/h), which means that they’re able to carry more speed through turn 3 leading onto the straight.
A closer look at the telemetry data reveals that the JK’s have a tough time on initial turn-in, but then they exhibit impressive grip through the middle part of a corner once they’ve taken a set line through the corner. The MRF’s, on the other hand, seems to struggle under load transfer – this is especially evident through the parabolica at turn 10, where the MRF’s lose a substantial amount of time to the others. Perhaps the softer sidewalls are a liability here, and it’s likely that the higher weight isn’t helping either.
The Goodyear’s prove to be a well-rounded tyre, although they do tend to screech quite a bit at the limit. The Apollo’s, on the other hand, provided the best performance of the lot. They were the most responsive and consistent around an entire lap of the BIC.