Rim width/tyre compatability

new2br

Hi again - bit of a followup from a previous post on new wheels...

Probably gonna get some cheap chinese carbon clinchers now, just to tick the box and put a smile on my face that the bike looks cool with deeper rims without breaking the bank on branded ones that are by the sounds of it they not gonna transform the performance speed/time wise.

So now to decide on best rim width tyre combo. With trend going towards wider rims and reading posts which have been a bit inconclusive (that Ive seen) on affect of various tyres on various width rims - I was hoping for some clear sound advice so dont run into fitment/rubbing issues as and when I get new wheels.

So if I get 23mm rim should I pair it with 23c tyre or 25mm tyre. From looking at some factory wheel spec usually the wider rims tend to be paired with the 'next size up' tyre so a ~23mm rim they say works best paired with 25c tyre. Am a bit confused as to why that should be the case as I Id have thought a tyre which is same with as rim to be more aero - but thats an uneducated assumption...

Anyway for my own purposed I've tried a set of zonda wheels on my winter bike which has 25c tyres and put them on my good bike which the new wheels are for - Cannondale Super six Evo HM. There is no rubbing and clearance is OK round the brakes. The clearance at the rear stay is prob just about ok maybe 2mm max either side with no load, so no idea how much wheels could flex if putting down the power - I'm guessing I couldnt go any wider that what the zondas are showing with 25c Mich Pro 4 (which I also read is one of the bigger tyres for the size) which would probably rule out a 25mm rim unless ok to stay with 25c tyre if it doent balloon out much wider.

I sort of approached the whole wheel upgrade a bit arse about face in that I got new 23c Scwalbe One tyres (and latex tubes) but I would be much happier returning this items to get the best match for rim width.

Any advice again much appreciated...

keezx

IMO the best combinations are outer rim width= nominal tyre width.
My current favourite is 19C (internal) rims with 25 mm tyres.
Again IMO riding qualities prefer over aero , the last aspect is the least interesting , very tiny.
With some tyres you'll end up with a flush tyre with rim and with other tyres the tyre still will be wider.
The upper limit is more what your frame can take than anything else.

cmcdonnell

Depends on the wheel. I have a set of Bora 50C's with a 24mm external rim (17C internal) according to the guidelines I think I should use a 25mm tyre but when I put one on it would not clear my brakes and looked quite bulbous. Tried a 23mm trye which actually measured 24.5 with my calipers and looked perfect. Should be more aero and si plenty comfortable enough but to be honest I never found 23mm tryes on normal "open pro" type rims uncomfortable anyway.

keezx

[quote="cmcdonnell". Should be more aero and si plenty comfortable enough but to be honest I never found 23mm tryes on normal "open pro" type rims uncomfortable anyway.[/quote]

All depends on your preferred pressure, with 23 mm on Open Pro's you can't go very low like 23 mm on 18 C rims.

new2br

Yip I think some of my confusion is coming from external vs internal rim width in relation to best tyre. I've watched and read some factory wheel descriptions, eg the mavic Kyrium video clip for new 2016 wheels with updated wider rim mentions increase in internal width by 2mm to 17mm - so am guessing the ext width can't be more than 21/22mm yet they explicitly pair with 25mm tyre. Also the new dura ace wheels say they are wider at 23mm ext for use with 25mm tyre.

So that doesnt really follow the convention of Ext rim width=nominal tyre width rule - which I have to say sounds like a rational assumption that I thought was sensible, and hence why I'd bought my 23c tyres up front. However if 25c with a 23mm rim is more compatible then better to return the tyres.

With the clearance in the rear stay being 'neat' to say the least when I tested my 25c tyre/winter wheel on the good bike, I think its going to be too much of a risk to go any wider to say a 25mm rim if there is potential for the tyre to spread any wider - the clearance issue is at the widest part of the tyre, not the width of the rim itself as the rear stay tapers in and is narrowest at the where the tyre rotates as opposed to the rim?...

*Update
Sorry I should maybe add - the reason for considering 25mm rims is that thers more availability/build options for these as far as cheap chinses carbon clinchers go. Spect says they are 18mm internal and 25mm wide, so if a 25c tyre would suit well, ie no wider than the 25c I tested from my winter wheel then they still could be a good option?...

Bobbinogs

You are buying some snide carbon clinchers with the main driver being to put a smile on your face, so why bother with a lot of nonsense about trying to find the perfect match between rims and tyres? You are not riding an Olympic TT so don't fret over marginal differences...stick tyres on your bike, ride it and enjoy life!

new2br

Bobbinogs wrote:

You are buying some snide carbon clinchers with the main driver being to put a smile on your face, so why bother with a lot of nonsense about trying to find the perfect match between rims and tyres? You are not riding an Olympic TT so don't fret over marginal differences...stick tyres on your bike, ride it and enjoy life!

Well yes true I'm not persuing the perfect match that Dave Brailsford would be proud of in terms of achieving marginal gain.

But even so given that I can opt for one tyre over the other, given that I'd like to buy new tyres to go with the new wheels is it not best to try and get the correct/better match for the purpose considering its gonna cost the same? If I was just swapping with a spare set/training wheel then yes I wouldnt be so picky and lash on one of a number of lightly/part worn tyres I have laying in the garage.

Plus I would have thought that matching the rim/tyre optimally could help prevent issues like tyre ballooning out like a lightbulb or even pinch flats/rim contact - maybe not...

Better to say this is what I need to make a good job rather than this is what I have and make do with half a job. Only my opinion...

86inch

new2br wrote:

Spect says they are 18mm internal and 25mm wide, so if a 25c tyre would suit well, ie no wider than the 25c I tested from my winter wheel then they still could be a good option?...

Be careful here, a 25mm tyre on a 25mm external rim will probably come up at about 28mm which your frame or brakes may or may not have clearance for... If clearance is remotely tight I suggest you stick with 23mm tyres.