It has been over 80,000 miles since I replaced with new OEM front and rear brake pads. I am now getting steering vibrations while braking only on long drives.

I think that rotors need machining to eliminate vibration but I plan to change both pad sets.

How much life you get or replacing at fixed intervals at earliest performance issue is a good idea?

 

Pads are usually long lasting.. Getting around 5 years of use should not be surprising.
BUT your issues aren´t with Brake pads..

The TL Uses a hardcore 80/20 brake bias and the single pot caliper is very hard on the front rotor. The TL is prone or rather designed to warp cheapo rotors (That includes OEM).

Your options are:
1.- Replacing the Caliper to Dual Pistons from the Acura Legend.
2.- Replacing your Rotor with a High End Aftermarket Vented Rotor
3.- Doing #1 and #2.

Replacing the Pads will not do anything at all... You can replace it with a 1000$ brake pad and the issue still is going to be the Bias + Caliper + Rotor.

 

you can stay on the stock calipers, but toss those warped out OE rotors for sure
Aftermarket pads will make it stop better too, OE parts are a medium use for `average mom drives the car` type braking

Also you need to FLUSH the brake fluid ONCE A YEAR, every 2 year max between full fluid change. makes an instant difference in braking- old fluid gets moisture in it and compresses, wont hold against rotor imbalances
its easy with a vac brake bleeder tool $25 and $10 of fluid, or any shop can do for you for $100!

Special bleed order for the TL is driver/left front then clockwise around the car LF RF RR LR
no other order is acceptable!!!! Do USE DOT 4 fluid

 

I must brake a little harder than you, my front trick rotors get about 25,000 miles on a set of high dollar matching pads-
40kmiles if used in a sane manner

I replace them well before the wear limit, because pads lose ability to shed heat once worn more than 50% of their useful depth.
That's bad for braking~
Rears go about 60kmiles -regular rotors good pads
I late brake into the corner at a heavy pressure rate, and enjoy living near the mountains where its like having a track day that goes for 50 miles

Friends with same brake setup get 50kmiles on same front pads! RacingBrake is the maker

 

I would say if you are getting over 80,000 miles on pads and rotors, dont change a thing! Only change it if you are unhappy with the stopping power of the stock set-up.

I dont think that you can change them at set intervals as it might change depending on how much you drive and what type of driving you do. I am at almost 40,000 miles on my brakes and according to Acura dealership I am less then halfway through my pads.

 

You have to remember that turning rotors to make the pad contact area perfectly flat and eliminate the vibration that you are experiencing makes the rotor marginally thinner. This also makes the rotor more prone to warping again.

The previous owner of my TL had the brakes done at the Acura dealer at around 55K miles and they replaced the pads at all four corners and turned the rotors. I ended up tossing all that into the trash about 45K miles later because there was a lot of warping once again on the front rotors and I wanted aftermarket stuff all around. There was still plenty of life left in both the front and rear pads, but that meant nothing since the front rotors were beyond done.

Like others have said, get rid of the OEM rotors and replace them with good aftermarket ones. Then install pads of your choice. I'd say that after 80K miles, you definitely got your money's worth out of the current ones.