A widely followed trend in modern cycling is to opt for wider tyres and lower tyre pressures than were historically the norm. I don’t want to go down that rabbit hole today.
This short article recommends a cheap but accurate tyre CALIPER MEASURING tool. The need for this tool is because the actual tyre width is often very different than the stated tyre width on the box.
The ACTUAL, inflated tyre width is the one that you should use in your optimal tyre pressure calculation. A 1-2mm difference in tyre width really can make a notable difference in optimal tyre pressure.
Bike Tyre Pressure Calculator
Use This: Silca has the best, free tyre pressure calculator. Here.
That calculator needs the actual tyre width for it to be correct.
Digital Vernier Caliper
I bought a KYNUP Vernier calliper for £9 from Amazon UK and it has 10,000 positive reviews, this unbranded one on Amazon.com is $7 with 37,000 positive reviews!! Here is one from the EU but more expensive at Eur20.
You can use this tool to measure the internal rim width, the external rim width of your wheel and the inflated width of your tyre.
Notes
- You will find that the internal rim width of your wheel has a big impact on the measured inflated width of the tyre
- Rather than ‘buying the widest tyre you can because some YouTube guy says so’, take a little time to research the recommendations of your wheel manufacturer, especially if aero is a consideration for you rather than just rolling resistance. A super-wide tyre that’s 4mm wider than the rims on each side definitely won’t be aero.
- Two 26mm tyres from two different brands may each have different installed widths at the same pressure.
High-End Calipers
You probably won’t need these…
Last Updated on 4 October 2026 by the5krunner
Small things I always use
- Garmin 90-degree charging adapter: Charges your Garmin from any USB-C cable. Essential when travelling. I use one.
- Body Glide: The blue anti-chafe stick swimmers and runners carry. I use it.
- Speedo earplugs: Fewer ear infections and no cold-water dizziness. I use them.
- Dryrobe Advance: My winter changing robe for open-water swims. I use one. A cheaper option is the AONYIYI changing robe.
- Maurten: Race fuel that stays easy on the stomach. I use them.
- Beet It Sport nitrate shots: Beetroot shots I take in the days before a race. I use them.
- Garmin charging puck: The quickest way to top up before a session. I use one.
- Injinji: Toe socks that stop rubbing, so you run more. I use them.
- Ultimate toe protectors: Stop black toenails on long runs. They work. I use them.
- Compressport R2 v2 calf sleeves: My calf sleeves of choice. I use them.
- Cellucor C4: My pre-workout before hard sessions.
- TPU tubes: Schwalbe Aerothan, Tubolito and Pirelli SmarTube. Light, tiny spares. I use all three.
- G8 insoles: Adjustable insoles that are good. I use them.
- Cycplus Cube: A 97g electric pump that gets a road tyre rideable in two minutes. I carry one. 5% off with code THE5KRUNNER.
Watches and sensors
- Polar H10: My daily driver for waking HRV.
- Polar Verity Sense: My backup arm-worn HR sensor.
- Nomad bedside charger: Charges my iPhone and Apple Watch overnight. I use it, and many of their bands.
- Train.Red: The best muscle oxygen sensor I’ve used.
- Tymewear: Accurate heart rate and reliable ventilatory zones. I use it to pace endurance rides over an hour.
- Garmin Forerunner 970: A pro-grade triathlon watch. I use this.
- Apple Watch Ultra 4: My daily smartwatch. No phone needed on rides.
- Garmin Fenix 9 Pro: I’ve just bought one.
On the bike
- Continental GP5000 for everyday riding, and Aero 111 on the front for special occasions.
- Helmets: Specialized S-Works Evade 3 for road riding, and Rudy Project Wing for TT-style races. I use both.
- Ravemen FR300: A front light that mounts under your Garmin or Wahoo. I use one.
- Wahoo TRACKR Radar: I use it on one bike and Varia on the other. They perform the same.
- Garmin Varia RTL515: Radar that warns you of cars from behind. I use this model.
- Wahoo ELEMNT Roam 3: The bike computer that’s easy to use. I use mine on most rides.
- Favero Assioma Pro RS2: Accurate power pedals that swap easily between bikes. I use this model.
Home and indoor training
- NPE Runn: Makes my basic treadmill smart, sending more accurate speed and distance to my watch and Zwift. I use it.
- Google Wifi: Keeps Zwift connected in my pain cave. I use it.
- Apple TV 4K: Zwift on the big screen. I use two.
- Google Nest Doorbell (wired, 2nd gen): My video doorbell, running in both Google Home and Apple Home. I use it.
Health, recovery and sleep
- FreeStyle Libre 3 Plus: Shows how my blood sugar responds to diet.
- hDrop: Measures my sweat loss in summer and indoors.
- Fourth Frontier Zone: Checks my heart under load in hard sessions.
- Oura Ring 5: My partner’s recovery tracker of choice.
- Eight Sleep: A cooling mattress cover my partner and I use nightly.
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tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors. ID
Mitutoyo is the best, but Insize is extremely good price/value (about 30USD), almost comparable to Mitutoyo. I work in metrology laboratory…
word of warning. I have an affordable vernier caliper.. and it EATS it’s battery even when it’s “off”, I’ve seen the same problem with the ones we have at work too.
So I have to store it with the battery removed otherwise each time I go to use it the battery is dead.