Looking for bargain tires to replace white walls on my Roadie.  My back tire is a 150/80/b16. I would like to keep the white wall look, but don't know if I can alter the size any or what a cheap and effective brand would be.  Thanks for any educated thoughts on this.  

I;  Try these guys www.parts411.com.. I bought 2 tires from them. Mounted and balanced myself. I don't pay the shops here to work on my stuff        I purchased Bridgestones tires and shipping came to 227.00. I changed the rear from a 170/80-15WW to 180/70-15 WW. The front stayed the same size.
A 130/90-16 WW. The shipping was fast..I had them with in 3weeks.front tire was 75.00 the rear 125.00. The have a good slection of brands to choose from.
You  should be able to go up one or two tire sizes.
I have about 500 miles on them and they work great. Way better than the stock ones. HOPE this helps...scruffy