Bigger brakes needed for 17" wheels?

[benyandthejets]

I'm looking at some 17x7 on my local CL. Then I got thinking, is it unsafe to use 17" wheels with the stock brakes? I haven't had much luck looking for suitable 16s so I may be forced to upsize...

[RobMinhas]

Diameter of rim doesn't really factor into safe braking.....unless the rims are too small and they contact the calliper/drum.

17s are fine dude...

[Inodoro Pereyra]

Man, that is SO mean, seems like something I would post...

[benyandthejets]

Haha nice gif, but I'm not sure you are 100% correct. Its harder to stop something that weighs more, which most 17s would. Just trying to get other peoples opinions

[Inodoro Pereyra]

He is 100% correct.

It's true 17" wheels may weigh more, but the weight difference considering the weight of the car is negligible. Even if you consider the end-of-axle (for lack of a bettrer term) rotating mass (CV joint, spindle, brake rotor, wheel, tire), the weight difference in the wheel is still not important. But the brakes are there to stop the whole car, not just the wheel's rotating mass.

Bigger brakes won't hurt (much), but are not necessary just for changing your wheels. Now, if you were changing the wheels and tires of a truck for BIGGER tires and wheels, then yes, you'd need bigger brakes, but not really because your new wheels/tires are heavier, but because since they are a (normally much) bigger diameter, the wheel's momentum is much bigger, as it is the load portion of the lever the brakes are working against. (sorry about the clumsy explanation, but English is not my first language).

So, no, in this case, you won't need bigger brakes, unnless you increase the car's weight noticeably, or the engine's power.

[kulluminati777]

as much as i hate to admit it rob is rignt lol. I had HEAVY chrome 18" rims and i stopped from 150ish km's to a halt if there was a jam on the autobahn ok.........BUT in my opinion it could of been better. I have never been a fan of the stock calipers even with the 15's i run now. So i upgraded. For better pedal feel and ''bite''. Mostly for looks though lol. Also with a larger size than stock the original brakes look so tiny and helpless lol

[RobMinhas]

Haha nice gif, but I'm not sure you are 100% correct. Its harder to stop something that weighs more, which most 17s would. Just trying to get other peoples opinions

I'm just poking fun bud, don't take it personally.

But really though, Inodoro is spot on.

And what do you mean you hate to admit it Kull?

You're spot on about our factory brakes in big wheels, my rear drums in 17" rims is just embarrassing since I have flashy gold rims.

[kulluminati777]

lol im just messing with you rob

[RobMinhas]

I'm thinking on this a bit more and for a 17" rim bigger brakes wouldn't factor in unless these rims weighed a stupid amount.

But in instances with Trucks, SUVs and domestic cars that can fit bigger(22" rims) the rims would put more stress on the rims. The brakes apply a force to the driveshaft/axle which has a certain diameter. The larger wheel would mean a larger ratio of outside wheel diameter to shaft diameter so the brakes and wheels would be at a mechanical disadvantage compared to factory wheels and brakes. The brakes would generate more heat and you would use more fuel from the mechanical disadvantage.

[Inodoro Pereyra]

The larger wheel would mean a larger ratio of outside wheel diameter to shaft diameter so the brakes and wheels would be at a mechanical disadvantage compared to factory wheels and brakes. The brakes would generate more heat and you would use more fuel from the mechanical disadvantage.

If I'm reading this correctly (and there's no guarantees that I am), then no, not exactly. If you put bigger tires in a truck (or car, it's the same), you will use more fuel upon acceleration, because the wheel's momentum is bigger. But that has to do with the diameter of the TIRE, not that of the wheel, and definitely not that of the brake. In that case, the brakes WILL generate more heat when braking, but that's because of the tire's bigger diameter (the tire's radius is the resistance arm of the lever in this case, while the brake rotor's radius is the effort's arm) which creates more work for the brake to dissipate. But the extra fuel will be used to put the wheel in movement, not to stop it.

On the other hand, using bigger brakes will, almost always, increase fuel consumption slightly, due to the more friction the bigger rotors and pads generate.

[RobMinhas]

You've given me some thoughts to consider, interesting stuff.

I only mentioned trucks and whatnot because of folks who throw 22" wheels on their Buick whatchamacallsits and S10s when they come with 14" wheels from the factory.

Either way, as the original questions answer we can both agree that moving to a 17" rim is fine with factory brakes.

[Inodoro Pereyra]

Either way, as the original questions answer we can both agree that moving to a 17" rim is fine with factory brakes.

Definitely.

[wytbishop]

Truth is the stock brakes suck so upgrading is never going to hurt you unless you went to like a 13" rotor K-Sport kit or something ridiculous. It would stop like mad but the rotors are so heavy you would see a noticeable loss in acceleration.

When I do my rebuild I think I will wind up dropping some stupid cash on an exotic brake setup. Mostly because in an open style 17" wheel the stock brakes just look puny and brakes are the only form of bling I find acceptable.

[Silkwyrm]

[quote="Inodoro Pereyra"]
(sorry about the clumsy explanation, but English is not my first language).


I've seen a lot of your posts over the years. Your automotive knowledge is excellent, but what I really want to say, is that you shouldn't ever feel you need to apologize for your English. Your English is better than half the people for whom it is a first language.

Silkwyrm

[Inodoro Pereyra]

you shouldn't ever feel you need to apologize for your English. Your English is better than half the people for whom it is a first language.

Silkwyrm

Thanks Silkwyrm, that's very kind of you. (I don't buy it, but I appreciate it ). But the fact is that I'm well aware that somebody with a better grasp on the laanguage would've probably given a shorter and more easily understandable explanation.

Either way, thank you very much.