Your tyres need you!

Preamble:
Last week we had a glimpse into the philosophy behind the design of Tyres for F1 Racing Machines vs a Stock Car.

Considering the fact that your tyres are the only means of your communication with the road you drive on, they can either save you or kill you – depending upon what care you take in choosing AND maintaining them.

Here’s some more on how to look after your tyres…

Tyre Pressures – Do they Matter?

YES - they more than do! Here’re some basic facts:

1. The Tyres that come with your Car are the best suited for the purpose it’s intended for.
2. There’s an uncalled for mania in our Country to run down such OE Tyre specs, especially on the 80Bhp+ Cars.
3. When I say uncalled for, check out multitude of street cars in developed countries where none dare ‘up grading’ OE tyres coz then their Insurance Policies will become invalid and a crash out there, whether coz of tyres or not, can set one back by thousands in hard cash – assuming no life is lost!
4. Every ‘chosen’ Tyre has a ‘safe’ load bearing capacity - say 1/4th the ‘weight’ of a Car.
5. The Weight of a Car varies - from ‘Kerb’ to ‘fully loaded’ - for understandable reasons. This difference can be as much as 500 kgs!
6. The ‘ideal foot-print’ of a Tyre is a function of its inflation pressure when ‘cold’, AS WELL AS the load on it.
7. While in motion even a ‘correctly’ inflated tyre ‘warms-up’, coz of internal heat generation due it’s inevitable ‘flexing’ AND friction with the road surface. Consequently, the ‘cold’ pressures go up by as much as 15% on a high-speed cruise after some time.
8. All this is taken care of when carmakers stipulate ‘cold’ inflation pressures. They, however, take a medium route - by specifying cold pressures for ‘part load’, which is usually the case, and strike a compromise between fuel consumption - higher the cold pressures the better - and ride quality - lower the better.
9. Therefore, when going on a long trip, ‘fully loaded’ as is usually the case, inflation by +10% over the recommended cold pressures is highly recommended. The ‘effects’ of various degrees of ‘inflation’ are illustrated in the sketches below:
   
10. It’s obvious that one has to aim at correct pressures to give the best ‘foot-print’ between the tyre and the road.
11. Looking at above sketches, it may be noted that ‘under-inflated’ tyres will wear out faster from their outer edges and over-inflated ones from the middle. Only properly inflated ones can ensure even tread wear.

So how do we go about it!

Actually, it’s not that difficult, considering ‘Cold’ means when the tyres are at ‘Ambient’ temperature – ideally the first thing in the morning before one rolls off. Now that’s where crux of the problem lies. To overcome it, this is what you can do:

1. Ideally, you need a Tyre Pump and a reliable TP Gauge of your own - as most at the roadside are out of ‘synch’. If you find a foot pump bit of a bother, there are Battery operated ones available for ~ Rs: 500/-, which plug into the cigarette lighter socket.
2. Similarly, a good ‘dial type’ TPG can be had for ~ Rs: 100/- and a digital/self-calibrating type around Rs: 300/-. It’s strongly recommend that you buy your own tyre pressure gauge. Armed with this, you could also fill-up air at any pump, using your TPG.
3. What one can do and it works fine is that you get your Pressures corrected to, say (+) 10% per your Gauge’. Next morning before rolling off, check again with your TPG and let off excess pressure, if any.

Remember that Tyres under-inflated by as little as 4 psi can raise your fuel consumption by as much as 6% - besides seriously jeopardising their lives and thus your safety!

Next week we’ll discuss the importance of ‘Wheel Balancing’ and the need for their ‘alignment’.