Originally Posted by gurrala74
Thank you for your quick response on up size. Can you please give me the reasons for your opinion and also suggest me that anything to be done on my tyres or leave them like that till they warn out. If I have to change then, which tyre is more good than JK in the same size of stock ( I am asking this if I get a good deal of only tyres buy back from any dealer)
If you want outright grip, go for Michelin Energy XM1+. But they wear out faster. You can go for Bridgestone or Apollo Acelere for better longevity. They are on par.
Without upsizing to 15" (change steel rims to alloys - Neowheels, Plati, HR etc):
Michelin - Energy XM1+ or XM2 185/60R14
Bridgestone - Potenza GIII or Turanza 185/60R14
Apollo Acelere 185/60R14 - 82H
I would suggest you take the car to an alloy shop to ascertain whether the wheel arches can take 15" rims and upsized tyres. I would stick to 14" with a different profile (mentioned above).
Upsizing affects the performance, if done without a thought. The general rule of the thumb is, there should not be a difference in diameter of more than 3% wrt the stock tyres. You can get 15" tyres at a lower profile and still achieve this though. But lower profile tyres would affect the ride quality drastically. And, there are more chances of a bent rim/alloy.
Going a little wider, like I've suggested above would improve grip. Since yours is a diesel, it's always better to go a bit wider than the stock size, considering the extra torque generated, compared to a petrol. Wider tyres would offer better grip and consequently improve braking.
To answer your query regarding buy-back: some alloy & tyre dealers buy the steel rims and the existing tyres back. If your tyres have a considerable mileage, then it's better to keep them as spare. You will get peanuts for used tyres. The ideal time to change tyres and rims would be when the stock tyres are worn out.