Aera Trucks were not my first precisions, but they're the precisions I've spent the most time on. They're similar in feel to cast trucks as they do not add any mechanism to aid in slop stopping aside from having precision milled components, and straight axles. These changes allow for a truck that is similar in feel to casts such as Paris trucks or Caliber trucks, but with a bit more consistency which really shines at speed, especially when sliding. While they may not have a mechanism to stop slop, @Pats Risers sells inserts for many different trucks on his website patrisers.com, and I'm heavily enjoying his 3D printed insert bushings in my Aeras. These inserts make any truck have a more responsive turn, as well as adding some rebound and support through the turn. I want this thread to be for people to discuss the differences between Aera trucks, how they set their Aeras up, and why they skate them. Personally, I have tried the four "modern" Aeras (K3, K4, K5, and K6) and I have found myself spending the most time on the K5's. I do believe it all comes down to personal preference, but for myself I have found that K5's compliment my skating style the best at this current point in time.
In terms of feel, K3's and K4's turn a bit quicker than K5's or K6's thanks to their smaller pivot. They feature a small cylindrical pivot that allows for a quick and smooth turn. K3's have a more "linear" feeling turn than the K4's as they have less rake. If you don't know, rake is a measure of the distance between the pivot and the axle as shown in the photo below of Caliber 3's (rakeless left, raked right)
If anyone knows how much rake each Aera has please comment, as I do not know. I do know that K3's have the least, K5's are in between the K3 and K4 (I believe it's 2.5mm?) and K6's are more raked than the rest. The more rake the truck has, the quicker the board turns. Rake creates an inherent center point in trucks that is more noticable at higher amounts of rake and less so at lower amounts of rake. K4's are similar geometry to the K3's but with more rake. They feature the fast turning small pivot with high rake, resulting in a grippy, quick turning and playful downhill/freeride truck.
K5's and K6's on the other hand I have found to have a slightly slower turn, but it is smoother and more supported than the turn on the K3/K4 geometry. K5/K6 have a thick pivot which helps reduce slop and twitches from road imperfections and inconsistencies. In my opinion, the two pivots have their own advantages and disadvantages, and it may really come down to preference. However, I found the K5 and K6 ever so slightly easier to skate smoothly with the support of the larger pivot. I believe since the bigger pivot is less reactive, there has been times the trucks have "saved" me from mistake that would've tossed me on a more reactive set.
K3 and K4 use nylon braided pivot tubing stock to act as a pivot cup, and the K5/K6 have a custom poured silicone infused urethane cup. While Riptide offers aftermarket pivot cups for all of these trucks, I've personally found them to be slightly softer and less supportive than the stock options. I've found that all Aeras seems to feel their best when ran with the stock nylon tubing or pivot cups, with a tiny bit of silicone grease to keep things moving smoothly. I don't mind the riptide pivots cups as much in the K5/K6 pivots, but I really notice the different in the K3/K4's. I think it is due to the smaller pivots and forces being less distributed, because when freeriding K3's or K4's with riptide pivots, it is almost as if you can feel the pivot slop in your slides. It doesn't really do anything bad to you, but it doesn't exactly feel good. This full paragraph is completely subjective, as I know riders who would disagree with me, and some who would agree.
For setting up Aera trucks, I think the best place to start is on Venom HPF. I'm currently testing out a barrel and chubby combination of Riptide Krank bushings in my K5's, but all Aeras seem relatively easy to dial in with 85a to 93a HPF, and maybe a 95A if you're running a 30 degree plate. A simple bushing setup that should work for most riders in Aeras would be 87a/87a front and 90a/93a rear. I enjoyed running this combination in all of my Aera trucks as it keeps a good balance between stability and reactivity. If anyone has experience on any Aeras, questions about Aeras, or has different ideas of setting them up, throw them below!