I know this is COMPLETELY off the theme of my blog, but I wanted to put it here because it's useful.
I ride scooters every day, all day in Chiang Mai to see healers and to see people around town.
Here's what I've learned about police check points and International Driver's Licenses and the rules:
If you don't want to get an International Driver's License and you don't mind paying $15 USD in tickets every 3 or 4 days then you will be fine. When you get a ticket...that ticket RECEIPT is good for 3 days which INCLUDES the day you got the ticket.
So even if they motion you to the side of the road within 3 days of the previous ticket, you just show them your ticket receipt and they are super friendly and just let you go. So, if you rode your scooter or motorcycle often (and especially in the mornings) you would pay about $30 USD per week in tickets which is not that bad...or maybe it's REALLY bad depending on your budget.
Do NOT pay over 250 baht/day for a scooter...that is the going rate (actually a tiny bit high) for a 125cc engine. If you have it for a month you should pay around 2600-2900 Baht for the ENTIRE month which is a pretty solid deal -- that's including the helmet but NOT including insurance for the bike itself...just medical insurance for you.
Now...if you had an International Drivers License with the box checked for scooters and the like, you would get out of the tickets. But if you don't mind paying a little bit in tickets you will be totally fine. Also, after 2:15pm it is somewhat rare to get pulled over...all the police checkpoints pack up for the day which makes driving sooooo much more relaxing.
But anytime before 2:15pm, expect police checkpoints very strategically placed all around the Old City, near the Maya mall, near the Stadium, and many other places.