All around the city there is a great risk of ticketing! At any place and any square feet of the town they have a special control office in the only interest of filling their public garages so you should avoid to go by car to Mainz. ! 1 hour parking costs about 4 Euro - the bus only 2 Euro! This rationed parking situation is look like in the former soviet union! It will cost you more than a flight from London to any place in Europe if you will miss to feed the local parking machines. Specially for handicaps & wheelchair drivers you should avoid to go to Mainz- because there are very few special public parking places for handicaps & no support in public areas and buildings!!!
Mainz is pretty average for German cities, which in other words means it is very safe. The area around the station, particular under the tall office towers straight ahead of the exit, and just to the right, tends to look a bit rough and harbour a few drunks, but nothing too serious. You might want to avoid the areas just mentioned at night if you feel vulnerable and are on your own, but personally I didn't feel at all concerned walking anywhere around central Mainz whether I was on my own or not, even late into the night. There were very few beggars around, although there were two conspicuous tramps sleeping in the doorway of the shoe shop near the cathedral every night I was there, but they were harmless apart from shouting at passers-by. One thing that Mainz did seem to have more of than other cities were crazies, but the ones I encountered were very friendly and especially keen to help me practice my limited German.
Ingelheim is a little town near mainz. Up on a mountain called waldeck, there is a nice tower. From there you have a great view on Rheinhessen and the Rhine valley, which is rather wide here.
When walking around here, you will meet the tigers!
I visited Mainz on Feb 16th ,2002 by train from Koln and I was pick pocketed at Mainz train station. It was an extremely professional job - my wallet was left intact in my inside pocket, but with the money taken out - all 100 Euros of it. Of course, I reported it to the local police who were extremely helpful, but honest. Because it was cash, there was very little they could do for me there and then.
Mainz is a big tourist draw, so naturally thieves will congregate there, especially at the train station. Be extra careful and vigilant with your possessions when visiting.
This area of Germany is extremely safe in my opinion. The people are nice, there aren't any straigh up theives, few backpackers, and mostly older tourists who won't steal. Still, keep an eye on your stuff. Everything is very people in the small Rhine River towns like Bacharach, St. Goar, Boppard, and Bingen. Check um out.