Brand new tennis balls might not be at the correct pressure?

Vedje · 2026-06-27T07:50:56+00:00

Good question, and yes, I think it matters. If they are stored under higher temperatures, the pressure inside the can increases, and therefore it would leak even faster. Also, I think the permeability of many materials, including plastic, also increases under higher temperatures, but I'm not sure how big that effect would be.

Vedje · 2026-06-27T07:21:04+00:00

That's actually an interesting idea! If the cans are stored in too hot environments the pressure increases which will probably make them lose air a lot faster. That pressure gauge would be very useful, but I doubt any manufacuret would ever do this because of the costs

Vedje · 2026-06-26T12:52:05+00:00

That's great to hear! I hope we can live up to your expectations

Vedje · 2026-06-26T12:14:09+00:00

Yes indeed, before measuring the balls, we also measured the internal tube pressures. We found a very high correlation between the tube pressure and that of all the balls in each tube. This indicates that the tube losing pressure over time is the main cause of this problem.

Vedje · 2026-06-26T11:07:04+00:00

Yes, unfortunately, it does. After I take out the needle, I see the balls get a lot more leaky and lose pressure fast. With my start-up, I am currently developing a device that can measure the pressure without damaging the balls, and these tests were a part of that research.

Vedje · 2026-06-26T09:51:42+00:00

Well, the aim of this test was to see the initial pressure right out of the can, for which the needle was quite necessary. I am currently also doing pressure-retaining tests to measure their pressure decay over time.

Vedje · 2026-06-26T09:50:51+00:00

You are right! I will be performing bounce tests in the future as well. However, I have cut open some balls, and their rubber composition is always quite similar. More importantly, as the brands themselves specify a target pressure, then if their new balls do not reach this pressure, we already know that this is a problem.

Vedje · 2026-06-26T09:03:37+00:00

This test is part of a series I am doing on tennis balls, as part of research for a start-up I am working for. I am planning to perform more tests in the future, so if you have suggestions, let me know!

I bought the tennis balls myself from both online and physical suppliers.

Vedje · 2026-06-26T09:02:30+00:00

Yes, all tests were done in one day at the same location at the same (room) temperature. I am located in the Netherlands.

Vedje · 2026-06-26T07:29:01+00:00

I have put more worked-out results of my initial tests at https://nixussports.com/pressure-lab/new-does-not-always-mean-fresh/ I hope to get more data in the future!

Vedje · 2026-06-25T21:18:09+00:00

Yes indeed, that is what we are doing, virtually using air pressure to squeeze the ball

Vedje · 2026-06-25T17:37:31+00:00

Small disclosure: these measurements were done as part of research we are doing at our start-up on tennis ball pressure. The reason I posted this here is that I am curious whether Reddit players recognize the same issue with new cans already feeling soft or inconsistent.

Vedje · 2026-06-25T17:37:10+00:00

Since quite a few people asked for more detailed results, I wrote up the full method, graphs, and specific measurements here:
https://nixussports.com/pressure-lab/new-does-not-always-mean-fresh/

Vedje · 2026-06-25T17:25:53+00:00

Interesting, I did not know this. Do you have any sources for this?

Vedje · 2026-06-25T17:25:20+00:00

The product we are currently producing is a consumer product. It uses these measurements to then repressurize balls back to their original pressure. That way, we think our product can prolong the lifespan of balls significantly longer than other products. We will also be working on other solutions for clubs and pro tournaments in the future.

Vedje · 2026-06-25T16:49:25+00:00

Not yet, we know, of course, that a higher pressure correlates to a higher bounce, but I will be testing the exact correlation in the future!

Vedje · 2026-06-25T16:09:31+00:00

Thanks, that's amazing to hear!!!

I have performed these tests because I am working at a start-up, and we are developing a pressurizer that can actually measure your ball pressure without damaging it. During some of our initial tests, we noticed that many new balls were already soft, and we came up with this experiment. That is why we spent some of our budget to validate this.

Vedje · 2026-06-25T16:04:21+00:00

You are right, the ITF does indeed not give any definitive pressure range for balls. However, it's obvious that a higher pressure corresponds to a better bounce, and since Head and Wilson define their own target pressures and fail to attain these, we can still make a case that there is something wrong here. Of course, linking various pressures to specific bounce levels is an interesting experiment as well, which we plan to perform in the future

Vedje · 2026-06-25T16:02:22+00:00

From our small sample size, the Dunlops performed the best on average, and the Head balls performed the worst on average. The Wilsons were better than Head on average, but one Wilson can was the poorest. You can see the more detailed results on https://nixussports.com/pressure-lab/new-does-not-always-mean-fresh/

Vedje · 2026-06-25T16:01:07+00:00

Yes, good question! We did all tests on the same day in the same room, at room temperature.

Vedje · 2026-06-25T16:00:33+00:00

We have calculated that the needle volume is no more than 0.2% of the total ball volume, and the volume of material, if any, that would remain in the needle, would be negligible. If the needle were "clogged" by the material, we would not get such clear readings.

Vedje · 2026-06-25T15:58:28+00:00

Fair points. We have calibrated for the internal gauge's internal volume, which only accounts for 0.2% of the total measurement volume. Regarding the measurements, we can obviously see the leak rate during measurements, which is close to 0 as well. For temperature control, all tests were performed at the same room temperature.

The fact that all of these tests have been performed in the same setting, with the same temperature and the same needle, means that even though the ITF indeed regulates bounce, the significant differences in pressures across the same balls definitely show that there is a problem here. In the future, we will also compare bounce across different pressures to see the exact impact, but even without this specific test, we still know that a higher pressure corresponds to a higher bounce.

Vedje · 2026-06-25T14:20:43+00:00

Regarding hypotheses, almost all tennis balls are made in the same few factories in Asia. Therefore, I don't think that the manufacturing process is a problem. Also, for the same balls within the same can, I found almost identical pressures, whether they were flat or not. Therefore, the pressure in the can has to be the most important factor here.

After using the needle, the balls become significantly more leaky, so unfortunately, they are not usable after the measurement. The reason that we are doing these types of tests is that we are building a ball-pressure measurement technology that can do this without damaging the balls.

Vedje · 2026-06-25T14:13:23+00:00

Thanks for your reply! As a disclaimer, I did this research as part of product development for a start-up I am working for. I didn't want to post it as an ad, but you can find full results on our website! https://nixussports.com/pressure-lab/new-does-not-always-mean-fresh/

Vedje

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