Brake performance on 20s

[dvdchris45]

Quick 2-part question to you guys who have 20 inch rims on your ride or know of people who do:

Is your brake performance severely impacted by having a large set of rims and tires? IF so, would you recommend to upgrading to bigger brakes like the Rotora setup?

Thanks

[Gadgetjq]

If done properly there won't be any difference at all in braking.

As you go up in size with rims, you go 'down' the same amount in tire profile. I.E. you 'lose' tire height from the inside of the tire while the outside circumference remains the same.

Cheers

[cklinh]

^^^More metal at a further distance from the hub equals a higher rotational inertia (and more braking power needed to stop it).

[Sebas007]

^^^More metal at a further distance from the hub equals a higher rotational inertia (and more braking power needed to stop it).

Haaa cklinh...you were faster then me !!!

For the same weight at x vs 2x (distance from the middle of the wheel) it doubles the rotational inertia

Example (it just to explain the way it works....the number of pounds are fictive)

1 pound at 1 inch from center = 1 pound of rotational inertia
1 pound at 2 inches from center = 2 pounds of rotational inertia
1 pound at 10 inches from center = 10 pounds of rotational inertia
^^^
(maximum for a 20" wheel)


To go back to Chris' question...I think that if you have the big money for the brakes (2000$ !!) and can eat after buying it...I would make it...especially if you can keep them on all year long (you don't have winter setup like me...got 16's on winter )

Tells me which kit you wanna buy.

[Gadgetjq]

^^^More metal at a further distance from the hub equals a higher rotational inertia (and more braking power needed to stop it).

But you're missing the subtraction of quite a bit of rubber, steel belt and other material from the tire, some of it fairly heavy and in the same place the wheel is expanding into. In the end there may be some weight difference but we're probably pretty close to a wash with a decent set of wheels.

Cheers

[cklinh]

In my little world, metal will forever be heavier than rubber and air


And Sebas, I think rotational intertia is proportional to distance squared... so if you double (2x) the distance, you quadruple (4x) the inertia you need to stop...

Given that, with the extra metal replacing the air/rubber... you are adding a M*r^2, while subtracting a m*r^2... (M equals bigger mass - of the metal, m equals smaller mass - of the air/rubber)...

Now, this is all theory... I have NO idea how this would translate to the real world

[dvdchris45]

thank for the input...i found a good deal on some 20s and these suckers are of course considerably bigger than the 18s I was looking at..I know some of guys roll on 20s with no litle or probs but these tire size calculators never tell me any good news on 20s..

[Astro]

Don't forget that you can add S.S. brake lines What a difference!

[Sebas007]

In my little world, metal will forever be heavier than rubber and air


And Sebas, I think rotational intertia is proportional to distance squared... so if you double (2x) the distance, you quadruple (4x) the inertia you need to stop...

Given that, with the extra metal replacing the air/rubber... you are adding a M*r^2, while subtracting a m*r^2... (M equals bigger mass - of the metal, m equals smaller mass - of the air/rubber)...

Now, this is all theory... I have NO idea how this would translate to the real world

Yeah you are tottaly right !!

[gnegroni]

So, what brake upgrade would be recommended for his change?