When it was time for me to get new tires, I was just going to go with standard black – as I always have. But I did not have time to order them – I needed them that day so I had to bite the bullet, go an LBS, pay full retail, plus they only had red tires in stock. Way too flashy for me I thought. The sales guy assured me that they would look good with my black bike. I did not think so but needed them so I got ‘em.
Guess what…I love the color! They look hotter than a witch’s tata.
Anywhoo, orange or lime green sounds awful to me but so did red. Tons of places you can buy tires…try bike tires direct or any number of other on line places. Even Amazon.
As for the size, I don’t know what you mean by big but suspect that 23’s would not explode under you. However, my strong guess is that you will be much happier with 25’s. So I wouldn’t go so far as to say you need 25’s, just that you should get 25’s.