A general rule of thumb:
To get to those temperatures, if you don’t have temperature controlled wine refrigeration, reds can normally just be kept in a cool cellar. This is also called “cellar temperature.” Whites and rose’s can be put in the fridge for a few hours, and the bubblies longer.
If you need to use an ice bucket to bring your wine to serving temperature, first fill the bucket with ice about 4/5ths, then add water to barely cover the ice. If the “room” temperature of your red wine is over 65 degrees, immerse it for five minutes; whites and rose’s for ten minutes; and bubblies for fifteen to twenty minutes. Light reds such as Bardolino, Valpolicella, Nouveau and Plain Ole Beaujolais, and others of that weight should chill nearly as long as the whites.
There are certain restaurants around that, shall we say, are not wine savy. They tend to store their wine in places like the hall behind the ovens. When in such a eatery, the first thing I do when the wine comes to the table is put my hand around it. If the bottle is warm or hot, I demand an ice bucket. This invariably causes a huge commotion. Managers run over and inform me that red wine is served at “room” temperature; causing me to give them an education on wine service. Guests at our table turn red. People at adjacent tables move, or chuckle behind their napkins. This is the trouble that comes with learning a little about wine.
We’ve run a number of blind tasting tests over the years involving the same wine at different temperatures. Often, the differences are so dramatic that unsuspecting tasters actually believe that they are tasting different wines. In any case, we’ve found that moderately tannic reds like Merlot has been shown to taste “better” to most people at slightly lower than normal room temperature — somewhere between 60 and 65 degrees Farenheit. If your room is around 75, you’ll definitely need to stick it in the fridge for at least half an hour. After that (as Curmudgeon points out), it’s personal taste. I, for instance, don’t mind a bit more of a chill; and so I like a red in the fridge for at least an hour.
And of course, as previously noted, super high tannin reds like Cabernet Sauvignon, and many Zinfandels and Syrahs, need a tad less chill, yet still are preferred somewhere between 62 and 68. Many Pinot Noirs, as well as a many “country” reds from various countries, seem to be preferred somewhere between 50 and 60. Beaujolais and Gamay types, right down to close to the fully chilled level of 45 to 50.
Finally, once you find the optimal temperature for yourself, you should also consider the “warming” factor as bottles sit out — which is the reason why I always slightly over-chill. You see, I live in Paradise (Hawaii, where it’s always warm), and so it’s a common thing for us to just open up the freezer and grab some ice cubes to throw into our glasses of favorite reds.