Hello, I've been having problems choosing a tire size. I bought this bike off of OfferUp, the guy had 38 mm wide tires on it. I've been getting a flat almost every week, it's always right next to the valve. I'm just going to get new tires and rim tape.
I've been hearing that you should multiply the internal rim width (20 mm in my case) by 1.2.
24 mm wide tires just seems extremely narrow. Does anyone know the proper way to find tire width or should I go with the 24?
Thank you very much for the help.
by My-Lane
10 Comments
A lot depends on what you can clear on your frame? What kind of riding are you doing?
I like the way these two articles approach it:
[https://www.renehersecycles.com/myth-18-wide-tires-need-wide-rims/?srsltid=AfmBOopjXiU6t5qNJafhbA1BNvwag9lv5NTXk-yhkOnNlXB6-yt_6jBX](https://www.renehersecycles.com/myth-18-wide-tires-need-wide-rims/?srsltid=AfmBOopjXiU6t5qNJafhbA1BNvwag9lv5NTXk-yhkOnNlXB6-yt_6jBX)
and
[https://www.renehersecycles.com/how-wide-a-tire-should-i-ride/?srsltid=AfmBOorh8tH8MHi2cIDqtW5plQSdOIv6OLPus4h6oWkLLfbPnQhfNfe-](https://www.renehersecycles.com/how-wide-a-tire-should-i-ride/?srsltid=AfmBOorh8tH8MHi2cIDqtW5plQSdOIv6OLPus4h6oWkLLfbPnQhfNfe-)
Wrong maths. With 20 mm internal width you can go up to 2.25″ safely. And you should multiply it by 1.75-3. Suggested 24 mm tires (23/25) would never fit on that rim, they are usually used with 13-15 mm rims.
For optimal aero 25s are probably ideal but 28s will likely run faster
Use the inside measurement (as in your photo #2), then consult the following tire fitment chart:
[WTB Tire & Rim Fit Chart](https://www.wtb.com/pages/tire-rim-fit-chart)
First, let’s talk about those flats. If it’s next to the valve, as in on the inside edge of the tube, it’s not the tire that causing your flats. From the pictures the spoke ends aren’t recessed in the rim. I’d check the rim tape first. If it’s on the valve stem it’s almost certain user error. When you install a tube you need to make sure the valve is aligned perpendicular to the rim so it’s not getting lateral pressure pulling on it. I always put a little air in the tube while installing so it doesn’t result from it inflating into an awkward position. If you’re using a presta valve, that ring is not suppose to be tight. Being tight also pulls on the seams. Either just gently snug or throw them away.
Second, it looks like you have hookless rims. So I think you’re looking for this chart.
[ETRTO – Recommendations and Standards](https://www.continental-tires.com/products/b2c/tire-knowledge/tire-rim-combinations-etrto-standards/)
The math you’re doing has to do with aerodynamic efficiency. Don’t stress over if unless you want to go fast. Commuting I recommend 32mm wide Wider if you want to do some non-paved stuff.
Where is the leak on the tube? If it’s on the rim side, then tape is the problem. If it’s on the tire side, then you have a small piece of glass or other debris imbedded in the tire. These can sometimes be very difficult to find. A different tire could be worthwhile in that case.
18mm internal width (while narrow by modern standards) has no problem with 32mm. You don’t want to run less than 32. My hybrid bike is running the same 18mm with 32mm tires. New rim tape should hopefully fix the flat issue.
I have internal width of 19 and run 50mm tires with no issues. Wtb calculator says its okay as well.
The formula I use is internal rim width x 2.5 = max tire width. But if the rim is between 18 and 23mm you can run damn near anything.
Thank you all for the help. I’m going to average out the numbers I’ve been getting and get 35 mm tires.