big tires require big brakes?

gata119 · #1 10-03-2004, 04:55 PM

I am soon having my brakes checked, I also have 315/75/16 tires and tow a trailer 2 times a week (although the trailer has electric brakes). What, if any kind of upgrade should I be looking at putting on my truck. I know nothing about brakes!
Thanks!

sgauthier · #2 10-08-2004, 08:59 AM

tire size makes no difference, your stock brakes should work fine. your still trying to stop the same weight whether your using stock tires or 35" tires. the weight difference in tires shouldn't be a big deal.

gata119 · #3 10-08-2004, 03:56 PM

Good call.
Thanks

wod99 · #4 10-08-2004, 04:03 PM

They always promote bigger brakes if you go with bigger tires. It could just a scam to make you buy brakes though.
Here is a link for ya.
http://www.off-roadweb.com/tech/0311or_brakes/

bigtruck311 · #5 10-08-2004, 04:14 PM

in my experience with more than a few vehicles any time you go bigger with a tire it increases your unsprung weight witch reduces your braking capabilitys, i know my truck with 38" brakes alot difrent than a stock truck, i still have the stock pads and roters tho all i did was upgrade to stainless braided lines, but when my current pads wear out i know i am getting better roters and pads

gata119 · #6 10-09-2004, 06:14 AM

Thanks for the info and the site. Anyone have an idea on how much a brake upgrade will run me?

DaveBeach · #7 10-09-2004, 08:21 AM

Not so fast on disregarding tire size to brake requirements. I'm no engineer (Accounting, FSU, 1982) but am often told I think like one. The MECHANICAL ADVANTAGE the larger tires provides in placing resistance against the braking contact surfaces can be significantly greater for a given amount of vehicle weight. Think of it this way-- a 12-inch diameter tire could easily be locked up with the brake pressure exerted by a standard disc brake setup, regardless of the weight involved (but the tire would certainly be worse for the wear... ). A 36-inch tire, on the other hand, with the same disc brake setup would be subjected to much greater pressure/resistance (which results in heat, a major factor in brake underperformance). This is of course an extreme example, but tire size is a signicant variable in determining braking efficiency.

ToddTCE · #8 10-09-2004, 11:08 AM

Larger wheel and tire packages can most certainly use larger brakes.

Tires alone will not change this too much but if you replace the stock 16 with some 18s you'll surely notice a difference.

From experience; I took the alum 16s off and put on some MB's that were 18" and the closest set of tires I could find to the same diameter (or height) so to keep gearing close. Well let me tell you first hand the difference in weight (about 45lbs stock and 70lbs aftermarket if I remember) made a huge difference in the trucks performance. Or lack of.

But you asked about brakes.... not performance right? Same thing.

The added weight of the wheel while rotating at 70mph is going to take a hell of a lot more energy to stop than the lighter wheel.

Want to prove it in simple form? Ok. Take a 5lb rock on a string and swing it around your head, then replace it with a 7lb rock on the same string and see which one slows quicker when you want it to. Now do this with four rocks!

The bottom line is that YES larger wheels and or tires (considering they weigh more) WILL take more energy to stop them. And start them too, but that's the reason I took the MBs back off and they are collecting dust while I look for a buyer.

gata119 · #9 10-10-2004, 09:03 AM

Thanks for the posts! All the input you guys provide is why I love this board. (then again I have never been to any other message board to compare). Regardles though I learn everything I need to learn right here.

piperc · #10 10-11-2004, 08:54 AM

yes, i would reccomend bigger brakes with bigger tires. bigger tires sort of have the lever effect. unless u like doing brake work alot

:santa:

sagittarius1 · #11 10-18-2004, 11:30 AM

When you put larger diameter tires on a truck, your distance traveled per tire revolution increases. Then in turn, when attempting to stop in say 100', your brakes/rotors have fewer revolutions to work with in which to stop the truck.

When you upsize from say 29" to 35" tires your tire/rotor revolutions decrease by 17% ..... and so does your breaking ability.

MXMOTOGUY · #12 10-19-2004, 02:41 PM

Gata... you asked about the cost of a brake upgrade... think BIG MONEY if you go with a "big brake" kit. I followed the link above which shows the install of a set of AP Racing drilled and slotted rotors (14"!!!) and new calipers and then checked the price through Stillen... upwards of $3800.

I, too, am no engineer... (Finance, CSU, Sacto, 1990), but I do understand the effect of rotational mass on braking forces as explained above much better than I possibly could. If you are noticing a marked degredation of your braking performance, you may want to check some of the other threads on this site for performance-oriented brake pads, upgrade your ROTORS to cross-drilled for better cooling, and upgrade to braided stainless lines. I've heard about upgrade master cylinders, but not sure if they're available for our trucks ~ probably not necessary unless you're getting really crazy with tire size. Just my .02.... good luck bro!

frostby · #13 10-19-2004, 02:47 PM

I just grabbed my spinning cieling fan from one of the blade tips, and ouch, but it stopped, then I tried it again from the inside, and lost a finger tip! - the fan is still spinning... aaah, the blood.. oooh

Well, it really didn't happen but I like DaveBeach's explanation!

japickar · #14 10-21-2004, 06:58 PM

There's no way you could get 14" rotors to fit in the 16" rims anyway. How about some of the power slot rotors? same size as factory but claims better stopping distances. Thinking of trying some myself. Oh yeah, and there a little chepaer than 3800 bucks!
Here's the link:
http://www.powerslot.com/platm.html