Thanks everyone for your reply. Appreciate everyone's input.
I'm now very much thinking of getting R12, 165, 65 tyres.
One question, if I get 155 tyres wouldn't that be better?
@suzukialtomehran: Thats a good demonstration bro, this is EXACTLY the problem I'm having right now, and the tyres need to be a little lesser in width. This will solve all my problems. And yes right now the car is very very heavy and I'm concerned about this to..
So finally, I think I will get R12 165 65. What do you guys think? Shall I get 165 or 155?? I will be changing both my rims and tyres for this to solve the problems.
Also, right now my car doesn't go more than 95KMs... do you think this is causing this?? I've done alignment and balancing everything. CNG is also well tuned and changed engine oil today. All in all its very well maintained but why isn't it going more than 95kms?