The last  time I wanted to change my car tyre, there I was at a tyre shop near my place. I  called upon the sales person and asked for the price. 
 He did  told me how much it will cost me but the problem is, I have no idea if its cheap  or not. Since the shop never display the price [ like most car accessory shops  in Malaysia ], its hard to believe the sales person's price.  
 There a  lot of factors on the tyre price. Such as , the brand, profile , year of make  etc. Of course, you can do what I did back then. That is go to few different  shops and ask for the price of the same tyre. But, not everybody can do that. In  fact, this issue clicked my mind when my lady friend from office went and  changed all ger tyres over the weekend and the tyre shop sort of ripped her off.  Its hard to blame her because she is not a person that goes around tyre shops  and ask for price.
 Anyway,  after a quick search on Google, found this site which sells tyre online in  Malaysia. They offer wide range of brands and sizes. You just need to find one  that fits your car and order. Once it processed, you just drive down to the  selected shop and get it replaced. The cool thing is, you pay for it online and  don't have to pay anything when you visit the shop. So, minimal chances of  rip-off!!! 
 Unfortunately, I couldn't help my friend with her  purchase. But hopefully it helps somebody out there.
 And oh  ya, even if you dont want to purchase your tyre from this site, you can at least  get the approximate cost of your choice of tyre. It will surely helps you when  you negotiate the price with your neighborhood tyre shop.
 Good Luck!!
 
