I took a bunch of measurements on the Calipers as well so that I could make a thorough comparison between the two. It turns out they are very similar in size, except in terms of overall length.

First, I wanted to know how much farther the Tundra caliper protrudes outward versus the stock caliper. For a reference point, I used the wheel studs and a carpenters square to see how far the outermost surface of the caliper sticks out compared to the wheel studs. Notice that both calipers are nearly identical in terms of where they sit in relation to the wheel studs.

Stock Caliper...



Tundra Caliper...



I thought that there would be a big difference here due to how many issues people have with wheel clearance. It looks to me like the problem isn't the outermost surface of the 231mm caliper, but rather the surfaces/ridges between there and the wheel mounting surface. That section of the Tundra caliper is shaped differently, see pics below...

Stock...



Tundra...




Aside from the overall length of the 231mm caliper, it is very close in size (Measurements "A" & "B") and positioning on the vehicle to the stock caliper. I had read that the Brake Pads for the 231mm caliper were also much bigger than stock, and the measurements of the Brake Pad Cavity do support that.

With regard to the brake pad cavity, the difference between the two in measurement "C" was about 9/32" or a little more than 1/4". Once again, this corresponds to the 7/32” (or approx 1/4”) increase in the thickness of the rotor. I would assume the extra 2/32" is to allow for slightly thicker brake pads.. however that would only be 1/32nd on each pad. That might give you some extra life, but probably won't have any impact on performance.

Since the increase in the width of the brake pad cavity is mainly due to the additional thickness of the rotor, I also took a look at the length of the brake pad cavity.

The brake pad cavity on the Tundra 231mm caliper is 9/16" longer than the cavity on the stock caliper. This definitely allows for a larger brake pad surface area.

I wanted to check on another 231mm caliper specification that nobody ever really mentions. The two 17MM bolts that hold the caliper on are CRITICAL BOLTS and I wanted to make sure that they still got sufficient thread engagement with the 231mm calipers. I mounted the caliper without the rotor or the pads so that I could take a look at how far these bolts thread into the mounting holes.

Top bolt... That's got plenty of grab!



Bottom bolt, Looking GOOD!



Finally, I wanted to know how much unsprung weight I was adding by moving up to the larger 231mm calipers. I put them both on the scale WITH brake pads and associated hardware to check the difference in the weight of the calipers.

Stock Caliper



Tundra 231mm Caliper



I was surprised to see that the 231mm Tundra calipers actually weigh a little bit less than the stock calipers. In terms of weight you gain 5.7lbs on the rotor and you lose 0.3lbs on the caliper for a net increase in unsprung weight of about 5.4lbs per side.

Finally, while we're talking about calipers, I thought I should include some valuable information contributed by NelsonMD.

When I was purchasing calipers, I was offered an alternative to the 13WL.. it was much more expensive and the casting was 13WG. I wondered what the differences might be, and NelsonMD was kind enough to find out.