Touring tyre: 25C vs 32C

[Oaf]

Hello,

The P*nct*r* Fairy visited during the commute home on Wednesday -
typical, what with it being "The Hottest Day Ever...!" ((c) a tabloid,
2006), the fact that I was in a mad rush to get home AND I had a
dratted headwind.

It turns out that the rear Schwalbe Marathon on my tourer has finally
given up the ghost - not bad for over 13,000 km travelled on it.

Anyway, I have in my posession what looks like a possible replacement
tyre - the tread is slightly "slicker" than the ones on the tourer
currently. The thing is, the possible replacement is a 700 x 25C,
whilst the expired one is a 700 x 32C.

Two questions:

1. Will the 700 x 25C replacement fit onto my tourer (Dawes Galaxy
'04)?
2. If so, would it be OK to put it on the back wheel, or should I move
the tyre which is currently on the front wheel (another 700 x 32C) onto
the back and put the replacement onto the front?

Thanks for any information,

Oaf

 

[dkahn400]

Oaf wrote:

> 1. Will the 700 x 25C replacement fit onto my tourer (Dawes Galaxy
> '04)?
> 2. If so, would it be OK to put it on the back wheel, or should I move
> the tyre which is currently on the front wheel (another 700 x 32C) onto
> the back and put the replacement onto the front?

1. Yes it will.

2. It's probably better to put the new tyre on the front wheel and move
the worn one to the back. If one tyre is in significantly better
condition than the other you generally want it on the front to maximise
your chances of avoiding a front wheel blowout. You will also get a
small aerodynamic advantage from the narrower tyre by using it on the
front.

--
Dave...

 

[Oaf]

> 1. Yes it will.
>
> 2. It's probably better to put the new tyre on the front wheel and move
> the worn one to the back. If one tyre is in significantly better
> condition than the other you generally want it on the front to maximise
> your chances of avoiding a front wheel blowout. You will also get a
> small aerodynamic advantage from the narrower tyre by using it on the
> front.

Thanks for the prompt reply, Dave. Much appreciated.

Oaf

 

[James Thomson]

"Oaf" <[email protected]> a écrit:

> 1. Will the 700 x 25C replacement fit onto my tourer
> (Dawes Galaxy '04)?

Yes, but something a touch broader would be a better fit on your
not-so-narrow rims.

> 2. If so, would it be OK to put it on the back wheel, or should I
> move the tyre which is currently on the front wheel (another 700
> x 32C) onto the back and put the replacement onto the front?

I'd put it on the front and move the 32 to the rear. The rear wheel takes
more weight, and the fatter tyre will give better support and less risk of
pinch puncturing.

James Thomson

 

[davek]

dkahn400 wrote:
> If one tyre is in significantly better
> condition than the other you generally want it on the front to maximise
> your chances of avoiding a front wheel blowout.

....and, correct me if I'm wrong, but another reason would be because
you also want best-possible traction on the front wheel to minimize
risk of skidding (front-wheel skids being generally more problematic
than rear-wheel skids).

Also good old Sheldon has some stuff about pros and cons of mixing wide
and narrow tyres:
<url:http://www.sheldonbrown.com/tyres.html>

d.

 

[Pete Biggs]

davek wrote:
> dkahn400 wrote:
>> If one tyre is in significantly better
>> condition than the other you generally want it on the front to
>> maximise your chances of avoiding a front wheel blowout.
>
> ...and, correct me if I'm wrong, but another reason would be because
> you also want best-possible traction on the front wheel to minimize
> risk of skidding (front-wheel skids being generally more problematic
> than rear-wheel skids).

I wouldn't worry about that because a worn tyre has just as much grip on
the road as a new one until there's so little rubber left that the casing
is showing, and the chance of nasty blowout will hardly be higher unless
there's some obvious damage. In fact the wider tyre will provide the
better traction and suspension, but putting on the back to help with the
extra weight there is sensible (when there's plenty of clearance).

Tyre size also makes a slight difference to steering as it affects trail.

~PB

 

[Rob Morley]

In article <[email protected]>
Pete Biggs <[email protected]> wrote:
> davek wrote:
> > dkahn400 wrote:
> >> If one tyre is in significantly better
> >> condition than the other you generally want it on the front to
> >> maximise your chances of avoiding a front wheel blowout.
> >
> > ...and, correct me if I'm wrong, but another reason would be because
> > you also want best-possible traction on the front wheel to minimize
> > risk of skidding (front-wheel skids being generally more problematic
> > than rear-wheel skids).
>
> I wouldn't worry about that because a worn tyre has just as much grip on
> the road as a new one until there's so little rubber left that the casing
> is showing

Unless you consider that different tread compounds vary in "stickiness"
when they come out of the factory, and this changes with age.

 

[Pete Biggs]

Rob Morley wrote:

>> I wouldn't worry about that because a worn tyre has just as much
>> grip on the road as a new one until there's so little rubber left
>> that the casing is showing
>
> Unless you consider that different tread compounds vary in
> "stickiness" when they come out of the factory, and this changes with
> age.

Do modern synthetic compounds change with age, though?

I've noticed that some tyres seem extra sticky when brand new, but very
quickly normalise, then don't go on getting worse. Others can be the
opposite. I say "seem" because I'm not sure I'm not imagining it.

~PB

 

[Simon Brooke]

in message <[email protected]>, Oaf
('[email protected]') wrote:

> Hello,
>
> The P*nct*r* Fairy visited during the commute home on Wednesday -
> typical, what with it being "The Hottest Day Ever...!" ((c) a tabloid,
> 2006), the fact that I was in a mad rush to get home AND I had a
> dratted headwind.
>
> It turns out that the rear Schwalbe Marathon on my tourer has finally
> given up the ghost - not bad for over 13,000 km travelled on it.
>
> Anyway, I have in my posession what looks like a possible replacement
> tyre - the tread is slightly "slicker" than the ones on the tourer
> currently. The thing is, the possible replacement is a 700 x 25C,
> whilst the expired one is a 700 x 32C.
>
> Two questions:
>
> 1. Will the 700 x 25C replacement fit onto my tourer (Dawes Galaxy
> '04)?

Yes.

> 2. If so, would it be OK to put it on the back wheel, or should I move
> the tyre which is currently on the front wheel (another 700 x 32C) onto
> the back and put the replacement onto the front?

If it is a tourer-type setup with most of the weight on the back wheel,
I'd put the fatter tyre there.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

IMHO, there aren't enough committed Christians, but that's care
in the community for you. -- Ben Evans

 

[Rob Morley]

In article <[email protected]>
Pete Biggs <[email protected]> wrote:
> Rob Morley wrote:
>
> >> I wouldn't worry about that because a worn tyre has just as much
> >> grip on the road as a new one until there's so little rubber left
> >> that the casing is showing
> >
> > Unless you consider that different tread compounds vary in
> > "stickiness" when they come out of the factory, and this changes with
> > age.
>
> Do modern synthetic compounds change with age, though?
>
Pass. I'm really out of touch with tyre technology.