Add another drop in the bucket for Nokians. I did hours upon hours of research on the topic and finally decided on the Nokian Hakkas for my Pathfinder. Also picked up a set of stock alloy rims from a QX4 so I don't have to spend $50 - $100 twice a year to have tires swapped off a single set of rims. Since I like the look of the QX4 rims better, I'm using those as summer ones and had my Hakkas mounted on my stock Pathfinder rims.
Check the local classifieds as well as sites like craigslist and kijiji... the alloy rims I got from a guy on kijiji had all-seasons with 90% tread left mounted on them, and I got the whole package for $600. Bare steelies from Crappy Tire would have cost me $300.
I don't see any 14" tires in stock right now, but I picked up my set of brand-new 255/65R16 Hakka's for $520 from this guy:
http://stores.ebay.ca/TiresByWeb. Locally they would have cost me around $1400. Tip: He's in the states and ships UPS, which kills you with cross-border brokerages. Ship them to the UPS warehouse in Sweetgrass, MT, then go for a road trip and pick them up. $50 for US shipping + gas + GST is way less than $100 for Canadian shipping + $200 in UPS brokerage fees.
To answer the original question about tire sizes, this web tool for checking various sizes comes in handy:
http://www.miata.net/garage/tirecalc.html. In your case, driving on
185/75R14's you'd be going 3% faster than what you speedometer reads. Negligible, IMO.
Check the manual and make sure the speed and load ratings for your new tires are sufficient for your vehicle. The 89Q you quoted means the tires can handle 5,116 lbs of weight and are rated for a max speed of 160km/h. Should be fine... that's roughly double the curb weight and 160 is around the speed governors start to kick in. :P