Motor Vehicle Maintenance & Repair Asked by Morce1946 on March 5, 2021
My bicycle tires go to 60 psi, and I can easily fill them up from nothing with less than 10 pumps.
My car tires are at 32 psi, so shouldn’t they be even easier? Yet I have never heard of anyone hand pumping their car tires. Why not?
People do that. Sometimes, at least.
I have a high quality (high volume) bike pump at home, and occasionally I use it to check the pressure on the car, or to top off if it's obviously missing something. I find it 100% hassle free and not in the least problematic. But then I have a really good volume on that pump; also I can use my whole body to pump (the type where you stand on the "foot" of the pump and can pull/push the handle by using your full upper body weight/strength).
I would probably hate it if I only had my secondary "trail" pump, which rests in my bike backpack all the time. First of all, I probably could not even fit it to the car tire, as it has no separate tube, and secondly it would really be a huge amount of work to get all that volume in.
Besides, the not so technically inclined person might not even be aware that it is technically possible to do so (not every pump fits the car valves), and people may not be aware that bikes have higher pressure than cars anyways (well, they may be aware, but subjectively a bike tire looks so small and flimsy in comparison to a huge car tire... with a car on top of it ;) ).
Correct answer by AnoE on March 5, 2021
Your bicycle air pump is designed to provide high pressure air, relatively speaking to a low volume container, the bicycle tire. If you have a high performance tire, it will be even higher pressure than 60 psi and a lower volume. My previous tires were 120 psi but only 7/8" wide, a very small volume.
Today's fat-tire bikes will have lower pressures and much higher volumes, which would require more pumps than my tires, but is still a manageable task.
Moving to automobile tires, you have similarly low pressures, but huge volumes! Expect thousands of pump strokes to make a small difference in pressure.
In years past there were hand and foot pumps for automobile tires, but it was absurd to consider that people would use them, especially since service stations provided genuine service and air for inflating tires was free!
Answered by fred_dot_u on March 5, 2021
There is no theoretical reason why you couldn't use a bicycle pump to fill car tyres. Indeed I used a double barrel foot pump to pump the tyres on my wifes' bicycle last night that I usually use for car tyres.
What you have to consider though is that the volume of air in a car tyre is significantly more than that of a push bike. It's not that the pumping action raises the PSI of any give tyre by that pressure, it's that it adds the swept volume of its piston to the air contained within the tyre. Because a bicycle pump has to be small to be easy to carry, it typically only provides a small volume of air in each pump and you'd find that the time take to inflate a car tyre would be significant.
Combine the time taken with the fact that pumps usually heat up during operation and that you'd probably have to allow breaks to let the pump cool down so as not to damage it and you'd likely find inflating a set of car tyres with a bicycle pump would take many minutes if not hours.
In an emergency situation, a bicycle handpump could be used. However I'd always personally prefer to use a foot pump or ideally a compressor.
Answered by Steve Matthews on March 5, 2021
Huh? I totally do this. I’ve had tires with slow leaks, around 10 psi each month. You’d be surprised how effective a bicycle pump is.
How do you pump using your legs? That's easy. Don't bend your back at all. Stand up straight. When your arms are fully extended on the down push then bend your legs until the handle meets the end of travel. Check out this video at time :50 Its not a perfect display but you get the idea. Use your leg muscles not your back muscles to aid your arms at the end of travel.
I'm not sure of the exact make and model, but its similar to the one in the video. I've a couple of different ones, they all seem to work about the same.
Answered by zipzit on March 5, 2021
Because it's tiresome. The volume of a car tire is much higher. While the resistance for each stroke depends on the pressure, the number of strokes depends on the total mass of air you need.
Answered by user40628 on March 5, 2021
Yes you can, but as several answers here point out, the difference in volume between a bike and car tire make it less practical.
If you have changed a tire on a bike you know it has an inner tube that holds the air. Even if there is a small hole in the tube, you can fill the bike tire.
Most car tires today do not have tube. On more than one occasion I have had a car tire with a flat and the bead (seal between tire and wheel) was broken, and I did not have a compressor. I worked long and hard and no amount of adjusting and pumping ever got the bead to seal. With a compressor you can put the air in faster then it leaks out, so setting the bead is easy.
P.S. By 1955 tubeless tires became standard equipment on new cars well before the internet and videos of people sealing the bead with flammable gas/fluid.
Answered by James Jenkins on March 5, 2021
Because it only costs 1$ at the gas station to use their compressor, usually you only need to add air to your tires maybe once a year (or less), and I don't even own a bicycle. If you're efficient and remove all the valve caps first, you can usually top up all four tires on one use of the compressor.
So the cost of the time spent hand pumping, the nuisance of having to own and store a rarely used piece of equipment, and the (admittedly small) cost of the actual pump is overall more expensive to me than just paying to use the compressor.
Answered by user3067860 on March 5, 2021
Short answer: Technically possible but takes forever to do so. Even electric compressors could take several minutes to top up a rather big tyre. Imagine doing so with a pump 100 times less effective.
Answered by Dmitriy on March 5, 2021
I do it all the time, I think it's not the problem with the pump, it's rather the problem with people who own the cars. It's easy and hassle-free to use an automated pump maybe that's why people prefer it.
Answered by user40657 on March 5, 2021
For me the biggest factors that come into play as to whether to go manual or not are:
I have a $10 electric pump that does the trick and these days its all I use. In the past I used a foot operated bicycle pump for my tires.
Answered by Ruminator on March 5, 2021
Convenience
Many answers already note that the labor involved depends much less on the tire pressure (higher in bicycles) than its volume (much higher in cars).
In North America at least, it is common to keep tires filled with nitrogen instead of raw atmosphere to improve (long-term) pressure stability. Compared to that, hand-pumping not only increases labor, but also inconvenience with more frequent adjustments.
The retailer that supplied my tires also offers free nitrogen refills for the life of the tires, without appointment and usually without waiting. But even discounting the small value of using nitrogen, most gas stations offer free compressed air which will also do the job a lot faster and more easily, and requires no equipment.
So unless I've found myself at the side of the road with a tire that somehow went flat but will still hold pressure, why would I hand pump?
Answered by HonoredMule on March 5, 2021
As a result, they don't sell well, and so, they are sold even less. Seriously, go into Walmart and try to buy a hand pump made for cars. The selection is slim pickings, and the ones they sell coughslimecough only last a couple of pump-ups before they start tearing themselves apart. They are just that cheaply made.
I'm sure there's a specialist out there who sells an excellent automotive hand pump direct mail at USA-made prices. But I can't find his pumps at Target at 8pm when I have a leaking tire.
As such, I usually end up buying an electric pump, because they have loads of those.
Gearing. A bicycle pump is made to still take a reasonable effort to make 90 PSI of pressure. That means they keep the piston size (the amount of air it can pump) relatively small. At 30 PSI, it only puts up 1/3 the resistance of 90 psi - it is "too easy" to operate, which means you have a lot of wasted body motions, and tire yourself out. (you still have to lift your 40-pound leg!)
Hand pumps can only move as much air as their piston is big. They don't have a way to make the piston larger when pressures are lower. So a bicycle pump with its tiny piston is really geared wrong, and will take a long time and a lot of "lost motion" to inflate a car tire.
An automobile pump only needs to go up to 30-35 psi. So they make the piston bigger. Effort is about the same as the bicycle pump at 90 psi, but it goes 3x faster.
Answered by Harper - Reinstate Monica on March 5, 2021
There are three forms of bicycle pumps:
Now, are these suitable for cars:
I would say that unless your tires are nearly empty, one type of bicycle pump (track pump) works well. As an additional bonus, it's lightweight and small enough to carry with you in your car (although not lightweight and small enough to carry with a bicycle). I carry a track pump with me.
Answered by juhist on March 5, 2021
You literally cannot buy a hand tire pump with the right piston diameter and that can be pumped enough strokes to inflate a car tire. The quality is too low and the Bore size it too small.
Answered by user51233 on March 5, 2021
There's videos of people pulling off this feat on YouTube. Here's the first that comes up in a search using Bicycle Pump to inflate Flat Car Tire. The video is about 5:06 long but it really takes the guy about 4:30 to fully inflate it using a casual pace as he describes. There's some interesting comments in the video too about people putting it to the test.
A typical bicycle tire can inflate from fully flat I'd guess 15-25 pumps or thereabouts, the guy in the video probably does a couple hundred pumps.
ProjectFarm uses a footpump to do the task in comparison to cordless chargers Which Cordless Tire Inflator is Best? Let's find out!. He quotes the pump doing the trick in 1112 pumps in a time interval of 8:42.
Answered by jxramos on March 5, 2021
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