*cough*
Okay. I've been readin' throu' this thread and had a little bit of wondering.
I've owned several 4runners throughout the year, (and still own 2 of them today). Altho' they are 1st and 2nd generation runners, they still have almoust the same bearing system as the new ones.
First of all, I'd like to say that I can find few things on earth as ugly as a 4runner on "low profile".
But that's just my opinion, whatever floats yer boat or something like that.
Bearing and brakes:
Some of the 4runners I've had, have been on 38"x15,5" tires (wich weight about 50-60kg/100-120lbs aprox. per tire on a wheel)
Original brake system, and worked just fine. No issues on that, it took it about 3-5m (I'm not sure what that is in feets) more to final stop from 90km/h (aprox 55mph) on 38" than on the original 31"
The only problem was that the tires started slippin' alitle bit earlier if they were worn, like on all cars.
The bearings were still original on one of them, driven 140.000km (70k miles aprox.).
The other ones I don't know, and I recently replaced all bearings in the new rig because of the solid axle swap, but that one is driven 280Mm (around 140k miles I think) and had new bearings in 240Mm (120k miles), after about 180Mm driving on 35" tires, on original bearings. Now it's on 38" most of the time and on special occasions, 44" DC/FC
Of course, there is more stress on all vehicle components when so big and heavy tires are used, but still, by the look of what I've seen in my cars, it's not so much more. Of course, I'm an "home" educated mechanic, so maybe I'm doin' some things alittle bit different than other people who just "own" the vehicle (Ever thought about retightening your bearings, once a year?).
And of course, as I'm drivin' on so big tires, I'm always checking with all the wearing components, spindle bearings and wheel bearings, steering joints and other stuff that might break or wear throughout my years.
And FYI, I'm not the type of a character that uses soft hands while drivin' in rough conditions. Just yesterday I broke one of the brackets that hold the right rear shock. (Not original bracket, just a stupid design by the former owner...)
I've driven through ice that would normally crush the frontend of a vehicle (thanks to my homemade "bumper" it survived), and I've jumped few meters in open air.
So, I think, that these wheels will not have much effect on the bearings and braking.
But there's only one way to find out! Just try!