I wanted to get him that tire looking Adult Toys, but a friend said her dog got sick from it, so I got scared. I'm not worried about spending some bucks on a Adult Toys I know will last. The tennis balls and soccer balls were not left to be chew Adult Toys, they were sliced and popped in the process of playing fetch and keep away soccer.... Just looking for some new ideas. I never did find a better Adult Toys than the Kong toys, change the food you put inside to vary it a bit, but to be honest I think you have found the best ones so far. The other thing I use is a whole leg marrow bone from the butchers, fine if you can leave him in the garden with it, so not good for indoors It's inevitable to find a chew proof toy. I have tried and tried and my dogs demolish everything. Let me know if you find something please:) Good Luck My pup has sensitive tummy too. Also a voracious chewer. I give him 12" braided bully sticks. One will last 3-4 days and they are all natural and fully digestable. He LOVES them.