Tube Sizing: Small tube inflates to 32" and is suitable for 50- 90 lbs (this tube is best for summer months). Medium tube inflates to 36" suitable for 120 lbs or less. For very small kids, tube works great in water but the kiddos may be too light weight to slide well in snow. They can hitch a ride with an adult on larger tube. Large tube inflates to 40" suitable for 120-200lb. X Large tube inflates to 45" suitable for individuals up to 280 lbs and our largest is now the 68" which is for multi-person play.