Remember the days of Ask Jeeves, where you would type your question in full form to find an answer? Well, while Ask Jeeves turned into just Ask.com and has escaped most people's front of mind, people still like to type in their specific question rather than keywords.
SEO has evolved significantly since the days of jamming your website with every keyword that you can think of to improve your ranking. Search engines are constantly improving their algorithm, and blocking out cheats for marketers like me to use to help move higher on the results pages. While this means that a marketer's job continually gets harder, it also means that search results continue to be more and more relevant over time to the user.
SEO is constantly changing and can be difficult to keep up with. The most important thing that someone can do is to make sure that the website has relevant content to the user to maximize the results. More specifically, you want your key words to be directly related to your business. So instead of trying to focus on "tires" as your keyword, think about more specific keywords that would drive your specific business such as "off road tires" or "faster tire repair" etc. These are rather vague examples, but that is because nobody is going to know your business better than you well. These more specific, and usually longer keywords, help to allow the internet to better understand what your website is about and drive the correct traffic to you (rather than your competitors!)
No two businesses are the same; they have different strengths and weaknesses from each other. Find what your does better than anywhere else and focus on that. Highlight it and bring attention to it. If you focus on this, you will have the highest conversions from customers, as you will be targeting those who are looking for specifically what you have.