Good toys for aggressive chewer?

Hi everybody, I'm new here.  We've got a 1.5 year old chocolate brown Neapolitan Mastiff.  He's very big and very sweet, but a power chewer!  You know those tire toys?  Chewed to bits.  Big hard rubber bone?  Chewed to bits!  We laugh now at any toy that says "virtually indestructible ."  Does anyone have any recommendation s?  Better toys?  Ways to keep him from chewing so aggressively?  I'm about ready to give him the spare tire from my car!!

THanks

I have a 15mo Bullmastiff, and yes the Tire was in nickel sized bits all over my floor in about 10 minutes To keep him occupied we use real shank bones, kongs with frozen peanut butter, bullysticks and occasionally he will chew on his Gallileo bone (Nylabone). I've recently come to the conclusion that he prefers the toys that he CAN destroy! The Gallileo bone we've had for months and there is little damage to it but he doesn't chew on it very often. We are on our second tire and it is already missing a fist sized amount of rubber. The kongs are still the puppy ones that he first had as they are only interesting to him when filled, doesn't chew on them after they are empty. Stuffies die a quick death but he is HAPPY. I have had 2 stuffies live a couple months- a pink hippo with a soft rubber exterior and stuffie middle, when the first one died we bought another Real bones can provide days of entertainment as long as they are thick bones. He once had a neck bone(frozen) that he was able to bite in half quickly and swallowed some before I could get it. He threw up a piece of bone the size of a Twoonie---very scary! I have been told to buy go-cart or mini bike tires as they apparently last a long time, but I haven't tried or priced them out. Goodluck and let me know if you find anything.

oh, do be careful, there are toys that are green round things that "freshen breath" and have corrugated cardboard in them!  i think greenies makes them, and also the greenie toys turn into a sticky stuff when they try to digest them.  that came up in a post a while back.

We use a lot of the Merrick products.  Some of their products are more like a snack, but others (like Bully Stix, Flossies, Hooves, etc.) hold up pretty well and the dogs LOVE them.  Merrick uses all USDA approved sources and does not use artificial preservatives in their products, so they're 100% safe as well.  You can take a look at them here:

http://www.merrickpetcare.com/store/dog_treats.php

I'm a little late on this but wanted to say welcome to the site and congrats on the new rescue pup. 

Shiner is a heavy chewer and will chew on anything.  I give him plastic coke bottles (empty) to chew on and he loves them.  I take them away when he starts ripping off small pieces.  Also the cow hooves are a big hitas are any and all bones.  He's eaten through one tire and a couple of the large jolly balls attached to rope.  But he loves the jolly balls so much that I keep buying them for him. 

Kat