Help a newb out...

I just bought a new set of tires for my X and after searching for a 17" tube on Amazon I am not sure which size tube to get....

Tires are Shinko 244: 4.6 up front and 5.1 in the rear.

Thanks.

In my experience, tube size isn't very critical. I've ridden for miles with a 21" tube in my 18" rear tire! Anyhow just get something close. If you have to choose, I suggest getting it a bit smaller and it will be easier to install.

If you run low pressures and/or do much offroad, might want to consider getting heavy duty tubes for more puncture resistance.