I cycle a fair bit. I average about 100-120 miles per week and ride one of those skinny tired road bikes (yes, I wear the spandex and all that). For 49, I can keep a pretty good pace and regularly ride with guys 10 years younger than I am.
However, one day, I was riding up a hill and got passed by some guy much older than I am, wearing jeans and on what appeared to be a hybrid. In my mind I thought "what in the actual f**k!". I couldn't figure out what the bike was as I was huffing and puffing to go from 12mph to 13mph in hopes of keeping up, but couldn't.
Then, a month or so later, the same guy passed me again and I got a look at the bike. It turned out it was a Specialized electric bike. I was pretty impressed.
As far as tires, I hit 35mph on pretty much every ride I go on and have hit 55mph as my max. The tires and wheels on modern (good) bikes are amazing pieces of engineering.