40's do put a strain on the knuckles, but many seem to get by just fine with them. If I were to run 40's on the old maxx, I'd definitely upgrade the knuckles to RPM since they hold larger more robust bearings.
However, if your like me, you may want to rethink the "40's". I wanted the GT1 tires too. On a slower rig, they are fine. But, once you ramp up the speed, it makes the truck really squirrelly and hard to handle.
That's the primary reason I took them off my aftershock. I was running it with +3 pinions, a gear flip mod (so roughly +4 gearing over LST2) and an LRP28. Once second gear kicked in, then entire truck would shift to the side and the thing would just get totally unstable. I now run 17mm revo wheels/tires on it and it's much better. However, they aren't quite as tall as HPI GT1's, so I had to sacrifice some height.
This is where the traxxas 3.3 maxx tires/wheels came in. I just picked up a set for a great price. They will more than likely go on my savage next season as it's what I usually bash these days. A hair taller than GT1, a hair wider, but less sidewall. So it should handle better at decent speeds. Still more sidewall than the revo tires, but not much.
Here are some photo's I just took the other day of my tires... I have about 30 more photo's... with rulers... I have problems with photo-documentation of things.
In order L->R:
Traxxas Maxx 3.3
Traxxas revo talons
HPI GT (old stock savage)
Pro-line road rage MT
Traxxas t-maxx 2.5 chevrons
Face view (less at a time, so the road rage are gone):
Traxxas Maxx 3.3
Traxxas revo talons
HPI GT (old stock savage)
Traxxas t-maxx 2.5 chevrons
I like to keep tires like the maxx chevrons in the photo's as everyone has seen a set of those in their life. Well, anyone with any MT history.
