I've started experimenting with different tire size on my Metro project and as the previous members have stated... It's a give and take. You will have to choose your sizes carefully.
I actually made a spreadsheet comparing data from all the tire sizes available new in the market from sizes 12" - 15" within a specific criteria for my driving style, and based on this just for giggles I chose the tallest option available (within my criteria) and tested it and my reaction was just as what was said, I found that I had to overcompensate on throttle and the gain was surprisingly a total wash - no gain, but my driving style was severely changed and not for the best. But it was a test, and now I'm trying to find my next victim size of tires
In other words it can get tricky and expensive... But there is a potential gain with just the right tire combination, the trick is to find what that is for your gearing and driving conditions. A little research, patience, and used tire/junk yard hunting and you might just find the right one, then you can replace with an LRR tire if your size is available.
