Grab some G54 merch here - www.en.garage54.ru/ In this video we try three cars with three tire pressure settings to see how tire pressure affects braking. For business inquiries: promotion@garage54.ru
I love how you guys jump from practical automotive advice to off the wall projects like building a car out of logs in the forest. Many channels do one or the other but you guys do both very well.
Busses have other important proprieties other than braking. Busses also have to consider weight rating (how much weight each tire can support) to avoid tire bursts or tire overheating. Same goes for large trucks. But for normal cars, this video is correct.
Tire tread and overall condition is also just as important! Good tires can decrease stopping distance, prevent hydroplaning, be more resistant to punctures, and most of all prevent a blowout. You can check a tire's tread easily by feeling for the wear indicator, when it's flush to the rest of the tread its recommended to replace it. Be sure to go through the entire tire's width. Check your sidewalls for cracks from rot or gashes that aren't cosmetic. Check the date of the tire the newer the better, example would be 0923 9th week of 2023. Any imperfections such as cracks, bubbles.. Really anything that seems off should be looked into, doing these simple inspections could save your and or others' lives
The age of the tires 'allegedly' plays a roll in grip as well. I did notice that the Lancer tires were dry rotted. Tire quality as well as wear also would affect the distances tested. Great video, but in order to do a direct comparison, all vehicles would have to have the same brand/model of tire fitted, their date codes being within 3 months of each other, have a wheel alignment, last but not least; have the tires worn in 500-1500km on the car prior to the test.
you should change the order of testing to see if is fading with heat after each braking a smaller change would be more interesting to see if it makes any diference.
I've had arguments with friends about the recommended tire pressure, vs the tire maximum pressure too many times to count! Thank you for finally making a video that shows the data clearly! I want more of this with suvs, trucks, and crossovers!!
There is no need to have arguments. Simply tell them to go read their car owner's manual and then come back to you to apologies for disagreeing with you. If you try to hold a debate with them right there and then, they won't listen to you.
I'd love to see the same test done in wet conditions. Low tyre pressure could make a genuine improvement to wet weather braking as dry friction (Which is independent of tyre contact area) plays almost no part in wet braking as the layer of water between the tyre and the road will act as a lubricant, so hysteresis (Tyres grip on the roughness of the road surface by turning the energy required to make it flex into the roughness of the road surface into heat) in the tyre rubber becomes the sole source of grip. For this reason more rubber in contact at lower tyre pressure should mean more braking friction in the wet. It also means more aquaplaning in standing water though, so the recommended pressure is still the value to go for in the real world.
Two suggestions for you guys: Add a 2nd brake caliper to all 4 wheels, will it make a difference braking? and how many alternators can you attach to an engine? Some people have 2 on their trucks, but can you use 5, 10 or more?
very interesting. never taught that underinflated tires will brake worse, because the rolling resistance should increase. you can do the exact test for acceleration. I think it will be also interesting to
@@will24655underinflated radial tires actually have less contact patch than when properly inflated. The design of them causes the tread to cup inwards at the center.
first car 185/70/R14....exactly like on my car. This experiment is worthwhile. Citroën is known for its good braking performances (last time i drove a Citroën i nearly kissed the windshield after barely touched the brake pedal) and is avaible in Russia, why don't do this test with a Citroën (in the 70's and early 80's Citroën had the world record for the shortest braking distance at 160km/h and was fighting against Porsche in the same event)
i was a victim of low tyre pressure once. didn't check. had 15 pounds in the front left when i put the vehicle shiny side down. keep a tyre inflator in the boot and one of those pressure sticks in the centre console cubby hole - not in the ashtray just in case out of sight is out of mind again.
Mmm - good test BUT, you were all over the shop with braking start point. The differences more than enough to seriously skew those results. I suggest taller cones or signals at braking start point so you can nail the braking accurately.
The heating of the breaks is causing the longer distance after each pressure change, and time to cool down. Need to run more than one try per inflation amount.
@@keilveil9153 They lowered it way too much. .2, or .3 bar at the max will probably outbrake the recommended tire pressure, but not by much. There are too many variables involved (tire carcass rigidity, tire temperature, surface conditions, tire wear, tire profile etc) and the test was too simplistic. Plus the tires were junk. You could see the Mitsubishi's tires with cracks all around the rim. Those tires are cooked.
@@keilveil9153 it's some advanced science, it has to do with the PSI - pressure per area. The car is only so heavy, distributed among all 4 wheels, the total pressure forcing the rubber into the road is "less" than what is required to make the rubber bite into the ground. Essentially the flatter tyre acts like a large ski board. And, too inflated, acts like ice skates - just glides on the floor.
5:39. "The car has stopped." Vlad is awesome, but I couldn't help but chuckle at this observation ;). I was half-expecting to afterward hear, "the door is ajar."
instead of stopping distance, you could just measure surface friction of the wheels, remove nonsense variables like user performance. both overpressure and underpressure remove surface friction from the tires to ground.
I brought my toyota 4runner to a used tire shop to mount my new tires. All of my tires were pumped to about 75psi (5.2 bar) or more! I asked the guy why he pumped it so high. He pointed to the max pressure on the sidewall lol. And once i brought my lotus exige to the lotus and exotic car dealership for a recall. I picked it up with the tires pumped up another 15psi (1 bar) over what I had ser it to. They even forgot to bolt the battery back down. I took the lotus to the track and almost wiped out on the warm up lap. And then the battery got thrown around and damaged my fiberglass body and spilled acid everywhere in the trunk Lesson learned
With drum breaks you have to jolt the breaks in reverse to adjust them you'll stop better with properly adjusted drum breaks and yes they're supposed to just work themselves but if you don't break hard a few times going backwards they don't actually do anything if you don't break hard enough whenever you back up
@@michaeljucius9509Not apocryphal to those of us who have worked on drum brakes. There is a "self-adjuster" that works when braking while traveling in reverse. Study a torn-down drum brake, and when you see some parts that even you don't understand, that'll be it. You're welcome.
Unless they can get an extremely large tank of air, a given 2 liter engine at idle (assumed to be idling at 1000 RPM) will process/require 1000 liters of air per minute, or 35.3 cubic feet per minute (a common air density measurement used with engine intakes). Assuming a redline of 6000 RPM, the same engine will suck 6000 liters of air per minute, or 211 CFM. The standard half inch air impact requires a measly 5-8 CFM at 90 PSI, and using one of them will drain a 20 gallon tank quite rapidly, as 20 gallons translates to 2.67 cubic feet. Granted, compressing air does change its density, but a standard 20 gallon tank compressed to 90 PSI releasing its pressure at a regulated 20 PSI of "boost" would still need to release that pressure at a volume that would empty the tank quite quickly in order to appropriately feed the engine. As for how I figure that, I'm dividing the RPM by two to account for "half strokes" where no air is moving (compression and power strokes), and then multiplying that result by the overall displacement (2 liters to make it easy) This works because each cylinder moves its air between two revolutions of the crankshaft (suck-squeeze, then bang-blow) Remember!! Engines themselves are air pumps, so the problem arises when you're trying to feed a 2,000 CC pump (engine) with a 150cc pump (air compressor)
I have a very Very good feeling that if you wouldnt have dropped the pressure to extreme levels and would have only dropped it in smaller increments you would have seen enhanced braking as you dropped pressure until you got to where the tread is rounding on its contact patch. Slightly lower pressure will increase braking but also increase fuel consumption. Higher pressure give better fuel economy being less rolling resistance with higher pressure being a harder tire, and thats also what causes higher pressures to brake worse. Because the tire is harder with less road contact.
I honestly would have thought that the larger contact patch created by lower pressure would allow for quicker stopping. I wonder what would happen without ABS on each of these.
Underinflating tires actually creates a smaller contact patch. When you underinflate a tire, the sides of the contact patch will have good grip but the center will have less grip because the tire has too little air to push the whole contact patch properly onto the road. When a tire is overinflated, the opposite happens. Having too much air creates a "balloon" effect where the contact patch is slightly rounded. This means the center will have the most grip while the sides will barely touch the road. Following the recommended pressure on the door sticker will ensure the tire has enough pressure to for the whole contact patch to properly grip the road.
@@angrysocialjusticewarrior Thanks for reading the wikipedia entry on tire pressure. I'll be sure to mention this to the places I learned auto repair at... over 20 years ago. It depends on how much a tire is over or underinflated as well as the type of terrain it is on and even the temperature it operates at. You forgot to mention things like that.
@@whyjnot420 The things you mention are not relevant to the discussion. Temperature is not relevant because the recommended pressure displayed on the door placard already accounts for temperature. Terrain is also not a factor since the recommended pressure provides optimal contact patch for both road and offroad conditions. It is only in niche circumstances where you would deflate tires to avoid getting stuck on an extremely muddy trail.
before watching, my theory, lower pressure = better braking as more surface area hugs the road fully inflated would reduce surface area but improve efficiency/steering.
@ Garage 54 -did you happen to see what the maximum pressure was on any of these tires? When you say “over inflation” is this past the max pressure value for the tire, not the label in the door jamb? I would be curious to know how a tire performs at Maximum tire pressure, which may not be considered “over inflation”.
You need to let the brakes cool before each test, overheating brakes massively increase stopping distance, and an emergency stop from 80kph puts a LOT of heat into thr brakes
after video: So, there's a coefficient of friction, too inflated or underinflated makes the tyre have less than optimal ground resistance, losing braking performance; and also the ABS is doing its own thing making it worse.
Monitor tire pressures with an IR temperature gun, change them to fit your personal use. Those temperature measurements also should be used to monitor wheel algnment, specifically toe & camber (thus caster). It works for me. I double the mileage out of tires & great mpg…of course, that also requires frequent attention…almost every stop & adjusting toe in parking lots…
I would go back to the original pressure to make sure nothing changed from slamming on the brakes. And to see if it stops on the same cone. It’s odd that less pressure and a larger surface area doesn’t stop faster. I guess it’s the way tires treads are designed it may be different on completely bald tires.
Interesting. Tyre dealers where I live always over inflate the tyres. They claim the manufacturers run them lower for ride quality. I have always reset them to the manufacturers recommended level as I feel they do testing not just working off a hunch.
This example would have been far better if you had replicated real world pressures. If the tires were recommended to have 32 lbs pressure, you should have filled them to 28/29 lbs instead of half or less tire pressure which is obviously going to be worse.👍😎✌🗽
@@MattyEngland 2.2 bar equals 32 lbs of pressure. Lowering it to 1 bar is dropping the air pressure to less than half recommended pressure, around 15 lbs. If they had dropped the pressure to 28 lbs which is 4 lbs under recommended, it would represent real world tire pressures. Not many people ignore their tire pressures when they get as low as one bar which I would estimate being about 15 lbs, because the tires will be noticeably flat. Plus, I'd like to see if underinflating a tire by a few lbs would actually decrease braking distance.👍😎✌🗽
By pushing the pedal until the ABS kicks in (It was noted at the start of the video that all cars have ABS) you're guaranteeing that the car is braking hard enough to lock the wheels. If there's less grip, less pedal pressure is needed to lock the wheels, but more pedal pressure won't stop the car any quicker, so it's not a useful thing to keep constant in the experiment in the first place.
привет Влад, Производители шин советуют накачивать до одной спецификации. автопроизводители в другой спецификации. насколько велика разница в безопасности и экономии топлива между ними. я накачиваю немного меньше, чем указывают производители шин.
They'd work, but the pistons would have to have a uniform cylindrical cross section for the whole stroke length of the engine for the rings to seal on them, so it wasn't as practical a solution as having the rings move with the piston.
DEAR garage 54 if you read comments? i hope this one gets your attention i was watchin one of your videos? and got to thinking what would happen if you were to force pure oxygen from like a scuba tank into the the intake of a car ? or if you replaced nitros with oxygen what would happen
I wouldn't necessarily say the test for the Lancer is accurate given how bad those tires are dry rotted, which means the compound is probably harder than when new. But still very informative for the most part!
I've noticed that you guys haven't done any experiments regarding top speed or high speed tests. Maybe something to consider? Get a car, and see what you can do to make it reach higher top speeds. Keep making changes to go faster.
They'd need a much better track with longer straights and plenty of run off areas to do that even slightly safely. The chance of killing someone rises dramatically as speed increases too, especially given the cars they use have no crash safety to speak of. You're literally asking them why they're not trying to kill themselves for your entertainment.
The Lancers tyres need to be replaced they have some serious wall crazing so are perished I would take it straight to a tyre suppliers and replace them before winter sets in.
Was there a cool down period between the different stops? Maybe some of the stopping distance was due to brake heat (fade), as the stops got progressively longer each time.
