Question on replacement rear shock collapsed/extended length - 3rd gen

Hello,
I have some 5160's on order getting delivered and will be installing them this weekend. I have a question on the change in collapsed and extended lengths between the stock oem 4600's and the new 5160's

Collapsed Length: 14.06" -> 14.22" (+0.16")
Extended Length: 22.90" -> 23.63" (+0.73")
Travel: 8.81" -> 9.41" (+0.6")
Sources:
4600's: Bilstein 4600 OEM Shocks Rear for 16-23 Tacoma 4WD 6Lug
5160's: Shock

I see Bilstein advertises these 5160s as being a 0-1.5" lift compatible. I do not see how this can be if their shocks have only increased the extended length by half of that.

Also, for the increase in compressed length, is there anything I need to do to account for this 3/16" change so I don't allow the shock to "bottom out" (if that is the right word).

My truck is a stock barebones 2019 TRD OR DCSB for your reference.

 

It's generally said that stock (or stock-fitment) shocks are good for "0 - 1 inch lift", so that extra ¾" would play into it being good for 1.5".

0.16" longer collapsed is insignificant, so you're good there (OEM design I recall builds in about 0.5" of leeway).

 

Yeah so all of those "for x amount of lift" numbers are bullshit and misleading. They really don't tell you anything and are more of a guideline. You need to do exactly what you are doing and go by collapsed and extended lengths. You also need to know the limits of the other suspension components such as bump stops, control arms, ball joints, axles, etc. But most people don't know any of this so they just use lift numbers to half-ass explain how much longer the shocks are.

For example, the limits for the rear suspension are bump stops for upper travel and brake lines for down travel (it's actually the shock but ill get to that). If you put a shock in that is too tall, the collapsed length of the shock becomes the limit and not the bump stop anymore. This is bad because that means you'll just crush the shock. The fix is to install taller bump stops (either by raising it or just installing a taller bump) so that those limit the up travel instead of the shocks. Pretty much the same story for the front shocks.

For down travel, usually the shock is the limit (or rather you want it to be). But beyond that, the brake lines become the limit but you don't want to rely on those for obvious reasons. So the goal is to make sure that whatever shock you are using doesn't extend further than the brake lines allow. You can always upgrade the brake lines to longer ones. But you can also only fit so long of a shock in before the collapsed length of that shock becomes too tall and you run into the problem I mention above. On the front, the limit is the cv axles. You can only use a shock that is about 0.5" longer in extended length (which gives 1" more travel at the wheels).

In your case, the extra 0.16" of collapsed length won't be a problem. The bump stops make contact well before the OEM shock fully compresses. And the extra 0.73" extended length should also be fine since the factory brake lines have more length than that already. But you can (and honestly would be good practise) verify this by flexing out your rear suspension and seeing how much play you have in either the shock length (when hitting bumps) or brake line length (when at full droop). That will tell you how much room you have for longer shocks.

Also, the OEM shocks are not actually 4600s so the lengths might be a bit different from the specs online. The 5160's should still fit without issues though.