Road Bike - Long or short presta tube valve stem?

I have Shimano R500 road bike rims. Rim depth is 24mm. Would I need a long or short presta tube valve stem?

either will work, but ideally should use short stems. i run these wheels and they arent so deep that you need the longer ones.

If it's 24 mm you will need the long valve. I have fitted short valves on my deep rimmed wheels when I had no other option but you need to fiddle about with pliers to get it fitted right which isn't ideal.

Edit- I don't understand phoster's answer. If you have deep rimmed wheels you really need to use the long valve. That's why they were invented specifically to be used with deep rimmed wheels. In my experience you wont even be able to use the short valves without using pliers to pull the valve through.

I always carry 2 spare tubes. I buy the long ones regardless of what my wheel needs. Some wheels can use the shorter stems, but having the extra stem length just makes it quicker and easier to check and top off tire pressures. Also, one day you'll be riding with someone and want to lend them a spare tube to get going again without fooling with patches. They might need the long one.

HTH

I've seen them sold in 36, 48, 60 and 80mm length. The 36 will probably work but might be a bit tight. If you can find the 48s use them. If you carry the 60s they will be long enough for almost any wheel so you can help out another rider if needed.