I have a 77 MBG. Among the plenty of multi things going on with the car, I had a flat tire. ("tyre", depending on where you're from) In the process of plugging for a temp repair I realized that I had three 175SR14 tires and one 185SR14 tire. How I didn't see this before, I don't know. Since they all are nearing dry rot, I'm going to replace them however I'm having different folks tell me what size the "SR" stands for. I have roto style wheels and I'd like to get a little more width to the footprint but still be okay. Any suggestions?