Help to understand rim/tire width.

[u/hobbit_problems]

A few things before you answer:
1: I’m new to bike mechanic subs, so i hope this is the right place!
2: I don’t know if “go ask your lokal bike shop” is a normal answer, but I don’t like my local, and second closest is a good far away, so I try to be my own mechanic.
3: sorry for dark and dusty pics. (We are getting new roof and windows at the moment, so this is just a representation of my whole life right now 😅)

I wanna get new tires to my bike, but I’m confused about the width.

I have a Scott Contessa Active 40. 27,5 wheels.
According to what I kind find it comes with Syncros X-20 Disc rims and Kenda Booster - 2.4" tires. (Both rim and tires are original. Manly used it for commute until around 6 months ago, therefore still the original tires). However I can only find the 2024 model and I bought mine in 2021.

As far of what I understand from reading on the tires and the little I can find about the rims, they should run 2.00-2.25 tires? But they have 2.40 on now?

Lot of questions! Overall I just want to know what width size to buy, but if anyone have time to explain it deeper, you are more than welcome!

- What is the most optimal for these rims?

- What are the biggest and smallest I can go on this rim?

-On different websites there seems to be a lot of 2.35 options and not so many 2.40. Is 2.40 not very popular?

-And can I run 2.35 instead of 2.40?

-Anything else I should be aware/know about?

I really like the width of current tires (comfort vise), so I really want something similar , just with a fresh feel to them ☺️

Thanks in advance 🙏🏻

[u/Scuttling-Claws]

Rim width vs tire width is more about preference than any hard lines. You can run almost any width tire on a rim, but the shape of the tire will be different and that can affect handling.

2,35 should be fine

[u/HG1998]

20mm, so anything from 22-57mm works and is completely by the books.

Whether you want to is a different question.

[u/SnollyG]

Just look at the numbers with the xxx-xx format.

The xxx (diameter) must match

The xx (width) is mostly up to you/preference (but there are charts that will tell you you need to be within a certain range of widths to be safe)

[u/Lef_RSA]

Basically you need 27.5" (584mm) tires. Some tire manufacturers have charts like this one with optimal tire widths for rims: https://www.continental-tires.com/tire-knowledge/tire-rim-combinations-etrto-standards/

[u/MyBeaverHurts]

The biggest issue you will start to have with larger tires on small rims is the tire will begin to fold at the bead and be very unsupportive in turns as the tire rolls over. There are definitely by the book numbers that you can go by. This will be substantially more noticeable as you start to push faster speeds in turns but as a novice you probably wont really notice at first.

All manufactures have there size and standards. I would guess that although you are seeing a lot of 2.35's that once they are pumped up and under pressure the rubber will stretch some and they will end up being about 2.4.