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OK, here's a puzzler for you all... I ride a wilier cento10 air.... great bike - love it!

I have a set of zipp firecrests which are obviously quite wide and run 25mm challenge elite tyres, which I also love...however... Wilier say the bike will take 28mm tyres, and I fitted some conti GP4000S 28mm to it, but they rub against the seat tube as the seem really high profile... there's plenty of clearence eleswhere and with the 25mm Challenges fitted, there's at least 10 mm clearence between tyre and seat tube.

Does anyone know of a 28mm tyre which is particularly low profile?? Or, is it just that inflating a 28mm on the zipps will create a more bulbous profile??

Cheers for your suggestions...

13 comments

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Canyon48 [1062 posts] 3 months ago
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Conti tyres often seem to come up a little larger.

My 28mm GP 4 seasons come up just short of 30mm and my 25mm GP 4000S's come up just over 27mm.

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check12 [229 posts] 3 months ago
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Conti 4000s are very tall tyres but they are also very wide, 25s are 28mm wide on my rims. (18mm internal rims). 

 

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BehindTheBikesheds [2292 posts] 3 months ago
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I found 4 seasons were tall too, I ended up buying some Giant P-SLR2 tyres in 28mm (circa 280g) and though coming up at 29mm wide on a pair of '01 Mavic SSCs they fitted just fine on my carbon bike. Problem is finding the 28s are nigh on impossible, not sure what Giant's newer range are like tbh.

Rolling resistance found the 28mm 4000 to come up at 29mm in height whilst the 25mm came up at 25mm on a 17mm wide rim, that 25mm tyre also measured 27mm wide when inflated. The Vittoria Corsa G+ is 24mm in height for a 25mm and that comes up at 27mm on a 17mm wide rim to. I bought a 28mm for when I wear out the Giant's but haven't fitted it yet though it weighs around 270g so only a few grams lighter than the PSLR but the vittoria is certainly thinner at the tread even than the conti 4000 and much less thinner than the Giant.

Wishing now I'd bought a dozen of the Giants at closeout from Rutland!

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bendip [47 posts] 3 months ago
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i couldn't fit grand prix 4000's in 28mm on my supersix or my tcr, 28mm vittoria rubino pro's (the old non graphene version) fit both bikes,if you can find them in 28mm they're worth trying, though the newer graphene range seems to have usurped em !   

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PRSboy [312 posts] 3 months ago
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I would imagine that a wider wheel would lower the tyre profile, on the basis that the rubber would be pulled wider, if that makes any sense.

Sorry, can't help on the tyre... though I will say that the 25mm Conti GP4000 has a nats chuff's clearance between it and the seattube cutaway on my Argon18 Nitrogen.

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il sole [95 posts] 3 months ago
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cheers guys...

I think it might just be trial and error then! thanks for the stats behindthebikesheds...

Bearing in mind i want to improve the ride quality by going to 28mm, I wonder if either sticking with the Challenge i have, or trying some vittorias might be worth it... 

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Joe Totale [63 posts] 3 months ago
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IRC make low profile tyres that are true to size. The only issue is that most of their tyres are quite expensive and they're also mainly tubeless. 

The Cycle Clinic who are the supplier of IRC tyres in this country have all the dimensions of the tyres when inflated on their site. It was invaluable for me as I needed low profile 25mm tyres that would fit under mudguards and went with them. So far I can't fault the tyres:

 

https://thecycleclinic.co.uk/collections/road-tyres

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BehindTheBikesheds [2292 posts] 3 months ago
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Joe Totale wrote:

IRC make low profile tyres that are true to size. The only issue is that most of their tyres are quite expensive and they're also mainly tubeless

The Cycle Clinic who are the supplier of IRC tyres in this country have all the dimensions of the tyres when inflated on their site. It was invaluable for me as I needed low profile 25mm tyres that would fit under mudguards and went with them. So far I can't fault the tyres:

 

https://thecycleclinic.co.uk/collections/road-tyres

This is going to be one of the big problems coming up, manufacturers don't want to have to be making different versions of the same tyre so now with the push towards tubeless as the new standard (certainly toward the higher end) there will be fewer good quality tyres that are non tubeless specific ( Schwalbe have already done this) and from that the prices go up too. 

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Vejnemojnen [288 posts] 3 months ago
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what are the internal width of your rims? IMHO, 28mm tyres are really optimal for 21mm internal width. Even 19mm rims perform better with 23mm ones (those will stretch out to 27-27.5mm anyways. At least I've measured bontrager R3 tyres on 19x622 bonty rims to be 27.5mm by caliper)

 

the lightbulb looks ridiculous, 28mm tyres are more uncomfortable on the same pressure as 23mm ones and they behave very weird during cornering.

 

Rule of thumb: rather than switching to wider tyres, you should switch to wider rims (ie.: KinLin XR31, Hunt wheels etc..)

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Nichola [6 posts] 3 months ago
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Conti 4000s are very tall tyres but they are also very wide, 25s are 28mm wide on my rims. (18mm internal rims). 

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the infamous grouse [62 posts] 3 months ago
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i had that issue  with gp4000 s II's on an oltre XR4. schwalbe durano 28c fit with room to spare.

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il sole [95 posts] 3 months ago
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Vejnemojnen wrote:

what are the internal width of your rims? IMHO, 28mm tyres are really optimal for 21mm internal width. Even 19mm rims perform better with 23mm ones (those will stretch out to 27-27.5mm anyways. At least I've measured bontrager R3 tyres on 19x622 bonty rims to be 27.5mm by caliper)

 

the lightbulb looks ridiculous, 28mm tyres are more uncomfortable on the same pressure as 23mm ones and they behave very weird during cornering.

 

Rule of thumb: rather than switching to wider tyres, you should switch to wider rims (ie.: KinLin XR31, Hunt wheels etc..)

Not sure of the internal width of the zipps - I think it's 19 with 26mm external. I've found 25mm to be OK, but I don't want to run high pressures... my winter bike runs (tubeless) schwalbe 30mm at only 50 psi and that's nice and comfy! Ideally i want to run a wider tyre at a lower pressure, but as i mentioned with the contis, there were ridiculously tall...

plus, i'm not getting new wheels!

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mrml [37 posts] 3 months ago
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Vejnemojnen wrote:

the lightbulb looks ridiculous, 28mm tyres are more uncomfortable on the same pressure as 23mm ones and they behave very weird during cornering.

 

Why would you run 28mm tyres on the same pressure as 23mm tyres?