Braking power: The relationship between tires and brakes

A popular question in the car world is one regarding braking power: How do I get my car to stop faster? Simply put, a moving object – in our case, a car – is stopped by friction. When you lock up your brakes and stop your wheels from rotating, you are transferring the stopping requirement to your tires. It is then up to your tires to create sufficient friction to bring your car to a halt. If your wheels are locked up, there is nothing that a big brake kit can do that isn’t already being done. On that same note, you can have the biggest brakes possible for your car, but if you have low-quality tires, it won’t matter.

Sure, bigger brakes can allow you to stop with less pedal pressure, as they create more friction sooner than the OEM setup. But, speaking purely about a situation where already you have your OEM brakes completely locked up, tires are the only thing remaining to bring your car to a halt.

If your car isn’t stopping well or quickly enough, it’s likely that you need better tires. If you install good tires and now your problem is brake fade, you need better pads. If you install better pads but now parts are overheating, you need bigger brakes or better airflow for cooling & heat dispersion. I’m not saying that big brakes are useless; rather, I’m saying that people often make the incorrect assumption that brakes are the primary (and, to some people, only) thing responsible for stopping your car.

Now that we’re on the same page, I’d like to make three quick points on the relationship between your tires and your brakes.

  1. After you’ve applied the brakes, your tires stop the car. If you’ve installed low-quality or undersized tires (for instance: stretching a small tire onto a wide wheel, which seems to be all the rage with some IS owners…), your brakes are powerless, no matter how big they are. If you’ve engaged the ABS, the only thing that will stop the car is stickier or larger tires. If, for some reason, you can’t engage the ABS, it’s likely that your brakes are worn out or your current pads aren’t up to the task.
  2. Your pad choice affects brake fade. A better pad can sustain higher temperatures longer before it will fade. This is true to a point – if you keep upgrading pads, you’ll eventually reach a point where the rotors can get hot enough to melt parts and ruin wheel bearings.
  3. If your pedal goes all the way to the floor when you brake, you likely need better brake fluid and better cooling because you boiled the fluid.

Now, with all that said, I want to make something clear: I’m not saying that bigger brakes are useless or that you will not thoroughly enjoy them. I could name offhand five or ten IS owners who have upgraded to either the Supra TT or the LS400 calipers and they’ll rave about their setup. My only goal with this write up is to make clear that your brakes and tires have an intricate relationship, and you cannot expect to stop well without both being of good quality.

Upgrading to bigger brakes is definitely helpful for people who plan on exceeding the stock/bolt-on power rating (ie: boost), but even the naturally aspirated folk out there can appreciate the improved “bite” that a BBK will provide. Just make sure you have proper quality tires to match!


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