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Car and bike questions? We have the answers

I have both a Santro Automatic as well as a manual version. I've noticed that the brake pads on the A/T car don't last as long as the ones on my M/T Santro. Am I imagining this or is this true?Raghav Negi, via emailWhen engaging forward or reverse gear in an automatic transmission, the brake has to be held or else the car lurches forward or backward on engagement. Similarly, when you want to slow down you can select the lower gear ratios manually to slow down but when you need to come to a complete halt, you need to have a foot on the brake pedal to prevent the car from moving forward. This way the brakes are being used more than with a manual transmission. Even when halted at traffic signals, the transmission should ideally be left in neutral mode. Some drivers keep the transmission in `drive' and the foot on the brake to prevent the resultant forward motion, which is the reason for accelerated brake pad wear. Modern automatics have a locking system that disallows shifting out of the `park' position unless the brake pedal is depressed. Does a high temperature affect the performance of an engine (especially diesel) adversely? Why? Raymond Pinto, via emailCar engines are designed to operate at an optimum temperature. An engine temperature higher than normal is detrimental to its performance. Higher temperature reduces the density of the incoming air-fuel charge and affects the manner in which the mixture burns in the combustion chamber. It causes the piston to expand more than is normal, sometimes resulting in piston seizure. Lubricating oil too gets burnt in the combustion chamber, which lowers the level of lubricant, which eventually starves the bearings and seizes them on the crankshaft. The loss of lubricant can also jam the valves in their guides in the cylinder head.I have bought a Gypsy and plan a long road trip soon. Now which tyres should I buy - off-road tyres or tarmac tyres? I have heard that specific off-road tyres are very noisy on tarmac. Also, do you suggest mag alloy wheels - the terrain I plan to take can be rough.Raman S, via emailSome off-road tyres, which are clearly marked for mud and slushy road conditions, are designed to obtain optimum grip on slippery and inconsistent road surfaces and maximum resistance on rocks and rough terrain. Tyres manufactured in India for 4x4 vehicles are usually all-purpose tyres designed for on and off-road applications, ensuring reliability and safety. These include Goodyear Wranglers, Bridgestone Duelers, JK Tornado, Apollo Storm and MRF Zigma GT. Mag alloy wheels dissipate heat much faster than conventional steel wheels and being lighter, reduce fuel consumption. However, they are susceptible to damage beyond repair at times. Imported tyres like the Pirelli in the Scorpion series and the Michelins are also worth considering. However, they are best fitted tubeless which fit ideally on alloy wheels.My Fiat Uno 1.2 petrol came fitted with Bridgestone radials but I find the tyres are too thin for the car. With roads getting slippery, I want to upgrade to a wider size on the existing rims. Please suggest the best tyre size, taking into conditions, road conditions and aquaplaning. Kurush Daruwalla, via e-mailThe Uno comes shod with 145/80-R-13 tyres. You could upsize to 155/70-R-13, which is available with most Indian manufacturers to improve the road grip. Subject to your vehicle's ground clearance, you could also fit the 165/65-R-13. However, fitting this size will reduce ground clearance, which, on uneven roads, would be a hindrance. Write in with your queries to wheels@thehindu.co.in





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