I am going to be flying Emirates, which limits checked baggage to 30kg, but doesn't appear to have specific size limits for luggage. I am going to be buying some new luggage and I would like to minimise potential issues when flying with other airlines. Do other airlines tend to have specific size limitations for checked baggage and what might they be?
Many airlines have a limit on size and/or weight for checked baggage. The size limit is frequently specified in terms of a maximum length+width+depth. However what this means for you if your bag is over this size is very variable. It usually means special handling i.e. they will still carry it, but you might have to collect it as a special counter at your destination. This may or may not be slower than regular baggage check. It might also mean an extra fee, often equivalent to paying for an extra bag. But in my experience this can be very flexible. Common items that are technically over the size limit (like skis) often don't incur an extra cost. Here are some example links1. 2
Simple answer: yes.
Long answer: they vary. I've seen some that look much smaller who I've fortunately not had to fly with (BMI I think). RyanAir is VERY strict. Fortunately, however, there are brands of suitcases etc that are 'carry-on' size and generally those are perfectly acceptable - as long as they fit into the overhead bin.
However, here's a chart for baggage restrictions for some major airlines. As you can see they're similar, but there are certainly variations.
In the US, the FAA has Carry on Restrictions. You can see the size here.
Some more airlines and their restrictions are on Wikipedia.
EDIT - I realise that you meant checked, not carry-on, so .....
This should answer your question for the majority of common airlines - courtesy of Wikitravel, is the huge List of Airline Baggage Limits - both checked and carry-on!
What you are really interested in is what the definition of "oversized baggage" is, since going above that limit involves sizable additional charges. As Karlson mentioned, 62" is a common cutoff for that, although I wouldn't call it a "recommended size". I also would not be surprised at all if the check-in agents would classify a long and skinny 48"x4"x4" box as oversized even though it tehnically meets the requirements.
It's also worth noting that Emirates does have size restrictions on flights to certain countries:
The standard free baggage allowance for flights operating to or from the USA, Canada and Brazil is determined for each single piece of luggage. For piece concept journeys, total dimensions (length + width + height) of each piece must not exceed 158 cm (62”). For Economy passengers with two pieces of luggage, the total combined dimensions of both pieces should not exceed 273 cm (107”).
They say that allowances for other flights are based on weight only, although I'm sure there are practical limits there as well.