The 18" wheels kit for P400 Defenders is now available from Lucky 8.

https://lucky8llc.com/collections/de...q-N9f_fszFnry0

Price isn't bad actually, since it includes shipping anywhere to the lower 48 (which has got to be worth at least a few hundred bucks for 5 rims and a set of chunky calipers.) Wheels look...OK. I wonder if the rear caliper switcheroo allows fitment of other 18" wheels, such as Redbournes and possibly even the stockers offered for the P300?

The rear caliper swap is my biggest concern, of course. It will certainly invalidate the LR factory warranty on brakes - or any issues they may generate. Braking performance will be negatively affected by mounting smaller rear calipers. The good news is that the only part being replaced is the calipers themselves, everything else (rotors, pads, etc.) stays the same, so performance degradation can't be THAT bad. On the other hand, if Land Rover decided to use larger rear calipers for the P400, they must have had a damn good reason to do so. Perhaps these will overheat too easily, there is less metal to dissipate heat?

Any thoughts? I am starting to think this may be the lesser of the handful of evils for those interested in a capable off-road setup and good choice of rubber for their P400s (the other evils being 20" with near low-profile sidewalls, or 19" with the current, pitiful tire selection.)

 

I'm intrigued. I've logged a decent amount of trail miles on my 275/55/20 AT3s so far and haven't yet run into sidewall issues, but I think that is more a matter of when, not if based on where we like to drive. I think I'm going to give my current set up one more season here in CO before deciding whether or not to do the caliper change. I'm less concerned about losing braking efficacy than I am just about the dealer trying to tie a caliper swap to something else down the line. And like you umbertob, I don't love that particular wheel option so maybe in 6 months we'll have a couple more choices. It will be nice to know if those wheel options are tied to the caliper swap or other 18s like you mention would fit.

 

I have not seen the P400 calipers, but I expect they will have a larger piston diameter than the P300 ones, in order to provide more braking force to the pads and disks. As well, the P400 disks will need to shed more of the resulting heat, as you note. Both will be necessary for support for aggressive, high-speed driving.

The pace of acceleration out of the corner must be at least matched by de-acceleration into it, or so I have been taught. If one reduces calipers, one should reduce acceleration, I suppose.