Low Profile vs High Profile tires

[rommelrommel]

19's clear my brakes and they are pretty large (14.96" plus 6 piston calipers). What size disc brakes do you have?

I think it's a 14.2" rotor on the front, but it's more the caliper that becomes a problem. SRT8, a lot of guys struggle with this because few companies make a 19" with the right backspacing and everything that also clears the brakes, but the tire selection in 245/45/20 and especially 255/45/20 for the rear is pretty grim.

Like I said tho, there are some 19's that fit.

 

[Midwayman]

Yes, I do so hate it when I run afoul of the "being able to stop too quickly" law.

Whats kinda funny is often the big brakes don't actually stop quicker. They have better fade resistance and more consistent pedal feel, but stopping quick isn't always a win. For example the 04-06 Acura TL came with 4 pot brembo brakes. The 5AT 2pot no names. The 5AT stops quicker despite being heavier. Once.

 

[phucheneh]

You could make that argument with any car, really. Have you ever driven a car that CAN'T brake past the tractional limits of the tires? As in, 'lock the brakes?' I haven't.

But a bigger rotor with bigger pads and more even clamping force is still pretty much always going to be some kind of improvement. I think the major differences tend to come from different pad materials; 'sportier' pads often don't bite as well at lower levels of pedal application. And with colder brakes.

 

[Midwayman]

You could make that argument with any car, really. Have you ever driven a car that CAN'T brake past the tractional limits of the tires? As in, 'lock the brakes?' I haven't.

But a bigger rotor with bigger pads and more even clamping force is still pretty much always going to be some kind of improvement. I think the major differences tend to come from different pad materials; 'sportier' pads often don't bite as well at lower levels of pedal application. And with colder brakes.

Yes, and they were scary. Just saying that 'big brakes stop quicker' is kind of a misnomer in the context typical street use. Pad composition tends to make more difference on the braking side of it.

 

[KentState]

I think it's a 14.2" rotor on the front, but it's more the caliper that becomes a problem. SRT8, a lot of guys struggle with this because few companies make a 19" with the right backspacing and everything that also clears the brakes, but the tire selection in 245/45/20 and especially 255/45/20 for the rear is pretty grim.

Like I said tho, there are some 19's that fit.

The first generation CTS-V where smaller while the 2nd has 14.96" or basically 15".

 

[Ferzerp]

You could make that argument with any car, really. Have you ever driven a car that CAN'T brake past the tractional limits of the tires? As in, 'lock the brakes?' I haven't.

At higher speeds, yes, few cars can lock their brakes immediately at 60 mph and brake size becomes a factor.

This is assuming decent tires. No, the slippery junk that goes on your family sedans isn't going to provide the traction to warrant a big brake, but when you have decent, and wide tires, you aren't locking them up on a dry surface at high speeds unless you hit a bump or the like and unload the weight from those front tires.

 

[rommelrommel]

The first generation CTS-V where smaller while the 2nd has 14.96" or basically 15".

I was saying that I think that the SRT8's have 14.2's on the front. I'm not quite certain... mine is for sale and my interest has waned. Caliper design rules out some 19's and virtually all 18's... I heard something about a company that specifically making a 18" wheel that could clear the brakes for SRT8 guys to have a reasonable winter/track option but I lost track of if it happened or not.

Just sayin that not everyone can drop down to 17/18" wheels.

 

[phucheneh]

At higher speeds, yes, few cars can lock their brakes immediately at 60 mph and brake size becomes a factor.

This is assuming decent tires. No, the slippery junk that goes on your family sedans isn't going to provide the traction to warrant a big brake, but when you have decent, and wide tires, you aren't locking them up on a dry surface at high speeds unless you hit a bump or the like and unload the weight from those front tires.

I will take your word for it and not go stab my brakes in the interstate.

Makes sense. A lot, now that I think about it. When rotors are warped (or have thickness variaton; whatever), but not absurdly so, it can be very hard to feel it at 50-60mph, but then suddenly become pretty jarring if you have to brake heavily at 70-80...I try not to do that, but bad drivers in this city can make it necessary.

I think my mind had previously attributed it solely to the 'frequency' of the pulsation in correlation with wheel speed. But it probably has a lot more to do with applying a far greater clamping force on the rotor, even if I don't think I am. Which would also explain why my rotors are warped in the first place.

(first car I've ever warped the rotors on. Makes me sad and kind of a hypocrite...although it's a far cry from what horror I've felt in other people's vehicles)

 

[Ferzerp]

At lower speeds, yes, every car can lock their tires, but at higher speeds, it's very difficult if your tires have any grip at all.

Get out on a country road that's empty some time, go 60 or 70, and panic brake and see how it works. You'll slow quite a bit before you lock the wheels if the road is dry and you have wide tires. But don't do this if you don't understand you have to be perfectly straight to do this

I know I can't lock my wheels at 60, and the following picture is actually the result of slowing down 60-30 with no tire locking, and no ABS engagement.

Oh yeah, and it also shows that mr herp derp "get a proper car" doesn't really know what he's talking about. It turns fine (even with a novice like me) Ignore the low acceleration G's, any time I've launched, I've not had it on the G meter, and it only saves highs when that's the active app.