Dan67 make a really good point here. Slime has been known to freeze. I do not know what temp it does so at, but this winter was brutal and I'm pretty sure it would have been lumps in anyone's tires. Anti-freeze is a good idea or, look for rockdoctor's recipe for tire sealant. It involves a number of ingredients such as latex, antifreeze, glitter, and maybe even slime. The only part I am actually sure of is the glitter. I don't think the color of it matters, but it may make it more festive when you do have to take the tires back off the rim.
l like to buy stuff and no I don't do payments!