Tires: 195 or 205 and whats the difference?, tiger paw, tire treadwear

Question
Bought a GEO 95 Tracker.  On my way to PO to get Owner's Manual got a flat. Tow took me to their service station where they replaced both front tires with 205/75R15, that's the size of all tires in use.  Believing I should replace the rear tires also, went online.  Learned that the original Tracker 4x2 used 195 and the 4x4 used 205.  Not knowing whether this is 2-wheel or 4-wheel, manual doesn't say and nothing within the car gives any clues, I checked the spare.  
It is a 195.  Nothing about wide track on the this tire. It's a Tiger Paw XTM (Uniroyal) Tread wear 400, Traction B and Temp B.  I cannot find similar info on the ''Radial Baja wide track'' tires.  Info on replacement tire: Treadwear 440, Traction A and Temp B.   Just found a linear ''bump'' in one of the Baja tires.  It's going to pop soon?  I don't plan to do any off road driving.  Many, many thanks from an older lassy with more guts than brains.

Answer
Bobbe,

You need to read up on tire sizing, and Tire Rack did a pretty good job of it:

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=7

I looked up your vehicle and the tire size for the 4X4 version was a 205/75R15, so I don't think this is a problem.

Tire Rack also did a good job of explaining sidewall indentations and bulges:

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=32¤tpage=33

So armed with that information, you should be able to figure out what you need to do - if anything,