Tyre size markings

[Amac]

Hi there,
Sorry if this has been asked before
I need to get some new tyres for my hybrid, I was looking to get something a bit road orientated, so I started to look at the markings on my bike and my wife's:
28 x 1x 3/8 x 5/8 -
28 being the wheel dia?
the other numbers being the thickness, but why two numbers?

Mine : 700 x 38C
Is 700 - 28 or 27.5
38 is 38mm wide but what is the C?

I did a bit of a google, but that has not made it any clearer to me
When searching on Evans and Halfords some tyres are in metric and some are in imperial.

So I am guessing 28 and 700 are the same size tyre, even thou 7000 is 27.5.

God I hope the question makes sense

 

[mjr]

The two numbers are a different width and height, but 28x1⅜x1⅝" is as close as makes no odds to 700C (700 is the tyre outer diameter in mm and C is a width/height marking which I think means 37mm) which is 622-37 in modern ISO sizes.

Tyre sizes are a mess: 28" is an arbitrary wheel size and annoyingly smaller than the 27" in 27x1¼", while the 26" in 26x1¼" is bigger than the 26" in 26x1.25". The only way to avoid this sort of insanity is to use the ISO markings with a dash between the wheel rim diameter and tyre width, both given in mm.

https://www.cyclinguk.org/cyclists-library/components/wheels-tyres/tyre-sizes is the usual reference work.

 

[Amac]

Gosh
Thanks for the link, that's a chart and a half...
I will go and have a look at my ISO sizes and use them, that's great.

As a side question, do you think an average rider, (I do 25-30 miles normally 3 times a week) would I feel much difference in a more expensive tyre?
I was looking at Continental ride tour and at some of the Schwalbe, or is it just one of those personal things.
Thanks for getting back to me.

 

[Ian H]

Bicycle wheels are always sized by total diameter including the tyre. So the same-sized wheel with a bigger tyre should have a smaller but wider rim. However it has all got rather confused with the advent of a standardised 700C diameter (622mm) for all widths of rim/size of tyre. ISO or ERTRO are the definitive numbers to look for.

 

[mjr]

Bicycle wheels are always sized by total diameter including the tyre. So the same-sized wheel with a bigger tyre should have a smaller but wider rim. However it has all got rather confused with the advent of a standardised 700C diameter (622mm) for all widths of rim/size of tyre.

I think it was confused before that with the UK and US different 26" sizes, if not earlier.

 

[mjr]

As a side question, do you think an average rider, (I do 25-30 miles normally 3 times a week) would I feel much difference in a more expensive tyre?
I was looking at Continental ride tour and at some of the Schwalbe, or is it just one of those personal things.
Thanks for getting back to me.

No worries. I don't think it's as straightforward as more expensive being more comfortable, as it's always a trade-off between comfort, puncture-resistance, speed and wear (and probably other things) as well as cost. Even within Schwalbe's catalogue, it goes from some pretty cushy cheap-but-more-fragile cruiser tyres to the tough-as-old-boots-and-some-say-feel-it Marathon Plus to their latest greatest "Schwalbe One" ranges.

 

[Amac]

Cheers guys, with my new found knowledge, I think I will pop up the local bike shop and go with their advice. thanks for all the info, cheers.

 

[Amac]

Well what a difference tyres make....I am sure its not in my mind, my new tyres feel so much less "crash/bang and smoother than my old ones.

Long story short, popped in my bike shop AW Cycles, and got the same size 700x38C Schwalbe. Got them home and put them on, even thou they were the same size, they slightly rubbed on the mudguard, they must have been a bit "taller"
Tried to file out the mud guard bracket, to give a bit more room but no luck.

Phoned the bike shop who said bring it down and they would have a look, but of course not to ride on the new tyres.
They had a look, but said they could get them to fit, but recommended some different tyres Schwalbe Marathon GT 700x35.
Which they fitted and the removed mud guard at no cost, which I thought was very decent of them.
(I know I might have paid a little more for them, but as a beginner I was happy as I was sorted out)

Anyhow, as I said I am sure its not in my mind, the bike feels really different. Just been out, and at one stage I thought I must have the wind behind me, so I turned round to check and I didn't

Anyhow, I am cuffed to beans with them, and I thought it was a good local bike shop story

 

[SkipdiverJohn]

Schwalbe tyres with a high level of puncture resistance, such as Marathon and M+, do tend to be a bit taller than average. This is due to the puncture protection layer under the tread. Despite what some say, I do not find regular Marathons at all uncomfortable or harsh, nor do I have any problem fitting the tyres to the rim by hand.

 

[annedonnelly]

Well what a difference tyres make....I am sure its not in my mind, my new tyres feel so much less "crash/bang and smoother than my old ones.

Long story short, popped in my bike shop AW Cycles, and got the same size 700x38C Schwalbe. Got them home and put them on, even thou they were the same size, they slightly rubbed on the mudguard, they must have been a bit "taller"
Tried to file out the mud guard bracket, to give a bit more room but no luck.

I'm pretty sure at some point Schwalbe started to make the 700x38C slightly bigger somehow. I noticed the same thing a few years ago. Very occasionally, with loaded panniers, mine will rub against the mudguard fixing.

 

[Amac]

I'm pretty sure at some point Schwalbe started to make the 700x38C slightly bigger somehow. I noticed the same thing a few years ago. Very occasionally, with loaded panniers, mine will rub against the mudguard fixing.

Yes I never realised how much different and choice there was with tyres, for me it has stacked out well, as my new tyre has a lot less ‘tread” but it still feels good on the road, and the bike shop it still be fine on canal paths and bridle ways.
Funny I had a google to have a read, there are so many choices even within one make.

 

[annedonnelly]

People want different things from tyres. As you've found the ones with "less tread" are faster on the road, but they wouldn't suit someone who wants to ride through forests & slide around in the mud

Hope you enjoy your bike!