Tyre size info/help

davidjordan75sqARC646

Hi everyone,
I'm looking for a bit of help/info as I need to change the tyres on my Trek FX 3.
The stock tyres are size 700x32 but I sometimes found them to be a bit unstable when I'm on a dirt path or some gravel. I'd therefore like to increase the width of the new tyres but will a 700x35 or 700x38 fit properly? Where can I found this out?
Thanks

Ben6899

Hi David, if you fit a wider tyre will it physically fit in the frame? You can look how much space you have with the 32 and then decide if you have room to increase to 35 or 38.

It's worth remembering that different brands measure up differently, so a Continental 35 will measure 35mm, but a Schwalbe 35 might measure 38mm. AS AN EXAMPLE, I have no idea if this is the case in real life.

You can find lots of anecdotal evidence online, of how people find particular tyres sizing up.

Then you have to be sure that your rim internal width is not way too narrow to accomodate a 35 or a 38. Are you already pushing the limits with a 32? What wheels do you have fitted?

Then you can look at the ETRTO tables or Mavic's research to find how much you are pushing it - or not - with the new tyre size (you're probably fine).

Good article by Mavic

arlowood

To add to @Ben6899's comments, the attached link gives you an idea of what tyre sizes are recommended depending on the inner rim width of your wheels.

https://www.wtb.com/pages/tire-rim-fit-chart

If your rim width is 16mm or lower then 32mm is about the limit of what you can fit safely. If the rim width is 17 or 18mm then you can get away with the larger tyres you suggest. Optimally you should be looking at 19mm or above for the inner rim width but I wouldn't be too fussed if your wheels are the narrower 17 or 18mm