# Why don't people hand pump their tires?

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?

• Back in the 1960's my Dad had a hand pump that was designed for pumping car tyres. – uɐɪ Aug 8 '18 at 14:56
• Sidenote: while it does work, you get an enormous pump in your arms from doing it. I'm not particularly well built, but my shirts fit funny for awhile after I pump up car tires. – Bryan Boettcher Aug 8 '18 at 16:20
• I've used a hand pump on car and light truck tires. It's orders of magnitude harder than pumping bicycle tires. I guess this is a factor of pressure and volume. Car tires have much more volume, trucks even more. – Don Branson Aug 8 '18 at 20:00
• @DonBranson: I guess this is a factor of pressure and volume. You guess right. The energy content of the air is the pressure multiplied by the volume. (If you multiply pascals by cubic meters, you get joules.) – Ben Crowell Aug 8 '18 at 22:18
• Why don't you just try to do it yourself? First hand knowledge, and all that, you know. And compare the two methods. – Vekzhivi Aug 9 '18 at 18:03

## 14 Answers

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 ;) ).

• I also use my track/workshop pump, and that's on a van with big tyres. I used to use a double-barelled footpump but it broke (when I used it on bike tyres; to get to 100psi I had to push on the ceiling). My 12V compressor takes longer than the bike pump and is noisy, so I don't bother getting it out. BTW mountain bike tyre pressures are comparable to car tyre pressures. – Chris H Aug 8 '18 at 16:08
• I still have a working footpump that was marketed for car tires, a few decades ago. And I stll use it occasionally, since the nearest gas station with an air line is about 10 miles from where I live. But that pump would probably explode a bike tire on the first stroke - the pump barrel is about 3 inches diameter and 8 inches long! Since you can use your whole body weight to operate the foot pump, using it isn't hard work and it only takes "2 or 3 strokes per PSI" when inflating a car tire. It will inflate a completely flat tire, it you first jack up the car so the tire isn't squashed flat. – alephzero Aug 9 '18 at 23:52
• The pump doesn't need the car to be jacked up to inflate a completely flat tyre. Jacking the car up will only have a very negligible effect. – Steve Matthews Aug 10 '18 at 9:57
• @alephzero: Your 3" diameter pump has a cross-sectional are of 7 sq. in. If the leverage on the pedal is 1:1 then a 200 lb bloke will create an air pressure of 200 / 7 = 28.5 psi. A bike tyre would sustain three to four times that pressure. – Transistor Aug 10 '18 at 20:39

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.

• Good answer, I've done this with a foot pump a few times and it took ages! A cigarette lighter powered pump was purchased soon after. – GdD Aug 8 '18 at 10:53
• Not all bike pumps are designed to be easy to carry. Most fairly keen cyclists will have a "track pump" at home and a smaller one to carry with them on the road. But that doesn't make any real difference to your answer. – David Richerby Aug 8 '18 at 16:06
• Besides occasionally allowing breaks for the pump to cool down, you also may need breaks for the pumper's muscles to cool down. – Lee Mosher Aug 10 '18 at 17:28

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.

• In the UK it is spelled tyresome. – kkm Aug 10 '18 at 11:58

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.

• 50 pumps is equal to around 5 psi for the tires on my Mazda 3.
• Learn how to use your legs when you pump. That’s way more efficient.
• I’ve found its easier and quicker to use the bicycle pump then it is to move the car into the garage, unwrap and replace 40 feet of air line to my air compressor.
• I now leave the pump in my car for emergencies.

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.

• Stating the metric of "50 pumps is equal to around 5 psi" is close to useless without stating the brand/model of pump. It'd also be useful to state the actual size of the tire. – Makyen Aug 8 '18 at 15:02
• I do the same. The bike stirrup pump is in the back of the car anyway for mountain bike trips, so it's ideal for the slow leaks. Had a case a few months ago - the car had been clean out, then discovered the pressure was low - tricky job changing the tyre on the camping field! – Philip Oakley Aug 8 '18 at 15:10
• I also do this all the time, although it has gotten a chuckle from passerby when I was pumping tires on my old (1986) camper van parked on the street. I check my tire pressure at home and if they are just 5 to 10 psi out I'm fine to spend 5 minutes pumping with my bike pump. Similar results also, I find 10 pumps = about 1psi. – Cameron Roberts Aug 8 '18 at 15:15
• With a traditional hand-operated bike pump, how do you use your legs when pumping? Most of the work is performed when pushing down on the pump, which doesn't use your legs unless you're jumping on the thing. You could use your legs when pulling the piston back up, but that's not the hard part of pumping up a tire. – Nuclear Wang Aug 8 '18 at 15:59
• See edit on pump size and how to use legs when pumping. – zipzit Aug 8 '18 at 17:37

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.

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!

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.

## Because big-box stores don't sell hand pumps of any quality.

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.

## Why are they different from bicycle pumps?

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.

There are three forms of bicycle pumps:

1. Track pumps. They are operated by your hands (aided by your whole body), and have a very long stroke. Most of these are optimized for high pressure (>100 psi / >7 bar). In theory, a good track pump could be dual action (pumping both on the "in" stroke and "out" stroke) but they are good enough even without dual action so most manufacturers don't bother to add the dual action feature.
2. Foot pumps. They are pure crap. The force is limited by your weight to the same value as track pump, but the stroke is limited by the ability of your legs to move. Stroke in foot pumps is much shorter than stroke in track pumps.
3. Travel pumps. They are small and lightweight enough to carry in a bag. The best of these can pump a high performance bicycle tire to >100 psi / >7 bar but it's a lot of work. The very best are dual action (pumping both on the "in" stroke and "out" stroke).

Now, are these suitable for cars:

1. Yes! Yes, even the high pressure ones work although a larger bore and thus lower maximum attainable pressure would be most ideal for car tires that are 2-3 bar as opposed to >7 bar in high-performance bicycle tires. A track pump can pump up a car tire. I have filled up often my car tires with track pumps and it works well. Under a minute of pumping with high pressure pump gives one tire enough additional air that pressure rises from lowest acceptable to highest acceptable. Low pressure dual action track pump would be probably 15 seconds per tire.
2. No! There is no reason for the existence of foot pumps. They are significantly worse even on bicycles, and on cars they are totally worthless. Don't buy these, they are worse for every single purpose when compared to track pumps.
3. No! Travel pumps can barely fill a bicycle tire to its maximum pressure. Car tires have much higher volume, and thus it takes very long to fill up a car tire with travel pumps.

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.

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.

For me the biggest factors that come into play as to whether to go manual or not are:

• how fit am I?
• how hot/cold out is it?
• how big is the tire?
• am I headed somewhere where I can't show up sweaty?

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.

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?

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.

• What is the point of posting this answer when there are multiple high-scoring answers saying you can do it, it just takes a long time? – Morce1946 Dec 8 '19 at 23:16

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.

• A decent "track pump" style bike pump (the minimum one would want for pumping car tyres) costs at least \$20. So, in your usage case, it's not really a small cost: it's enough to pay for 20 years of gas station top-ups! – David Richerby Aug 9 '18 at 13:46
• Where does it cost \$1? In Australia, the air pumps are free at any petrol station that has them... – Shadow Aug 13 '18 at 3:19
• @Shadow its not uncommon to pay for compressed air at a continental USA "gas station" (servo). – Criggie Aug 13 '18 at 9:33
• @Shadow in the US in the past, most gas stations also provided some automotive services, and so they had commercial air compressors running all the time, so providing air for free was an easy thing to do. Now, most gas stations are actually convenience stores with no auto service capabilities. Rather than trying to maintain a compressor, they have a third-party company bring in a small unit that provides air, water, and sometimes vacuum cleaning, for a fee. It sucks, because the compressors are weak and take forever to fill your tires, and you pay for the privilege. – barbecue Aug 13 '18 at 14:56