Mismatched tyre sizes

[Andrij]

This weekend I noticed that my new bike does not have matching tyres.  This is by no means a catastrophe, but I will – in the fullness of time – put on a matching pair.

The front wheel has a Continental Grand Prix 4 Season 700x25 while the rear has a Continental Grand Prix 4000 700x23.

I’ve never run different sized tyres on the same bike.  The previous owner confirmed that it was a case of replacing a damaged tyre with whatever was to hand.  Would it make any difference swapping them so the thinner tyre on is the front wheel?  Are they best the way they are?  Or are they too close in size to make any difference?

[Really Ancien]

Put the 23 on the front, the rear tyre carries more weight so you are less likely have have a snakebite puncture with a bigger tyre on the back.

Damon.

[kyuss]

Personally I'd swap them round. Fatter, more puncture resistant one on the back for the extra comfort where most of the weight will be. You could also argue that the thinner one on the front would be more aerodynamic too but I doubt if any mere mortals would notice that difference.

[delthebike]

What Really and kyuss said + Unless it is worn, in which case you shouldn't swap them!

[Wowbagger]

I'd think it would make no difference whatsoever. I suppose a wider tyre on the back makes more sense in that rear wheels support more weight - at least, when stationary and accelerating.

I have been running a 700C on the back of the Mercian and a 27" on the front. I recently replaced the 1¼" tyre with 1⅛", which gives me clearance for a mudguard.

Edit: wot they said.

[PaulF]

'fess up time!!

Twas me who put the tyres on and got too lazy to change them round the 'right' way. Thanks for your discretion Andrij

[Oaky]

Sheldon has an argument for each of the front/rear configurations.

[border-rider]

I've run a bigger tyre on the front of the audax bike a few times - as Sheldon said, it can help with comfort on long rides (less road vibration) and if it's a gnarly, gravelly, lanesy route the extra grip on corners is quite useful on the front. But mostly I use the same front & back.

[Andrij]

This is what I've come to expect from yacf: post a question just before leaving the office and have a handful of sensible responses by the time you get home.   

Thanks.   

[Basil]

I posted a similar Q on URC many years ago before all this forum nonsense 
There was a suggestion that it would be better to put the wider tyre on the front.  I can't for the life of me remember the reason though.
Perhaps something to do with what MV suggested?

[Tim Hall]

Keep the smaller one at the front.

That way you'll be going (slightly) downhill all the time.

[Biggsy]

For a while I used a 32mm front tyre and 28mm rear tyre on my tourer...

a) because I could.  Front forks can take a wider tyre than rear stays.

b) to get more suspension where I wanted it most without risk of pinch-flat with a narrower but softer tyre.

But 32mm was OTT really, so I settled on 28mm front & rear.

It's just as logical though to put the wider tyre where it takes more weight (when you can).

[Aidan]

I've a 28 on the front and a 25 on the rear , mainly as a stop gap measure , but I do find it strangely comfortable and may keep it that way

[Really Ancien]

I actually have different sized rims front and back on one bike. The rear wheel always takes more hammer because of the dishing, so that benefits from being heavier, the front can be lighter, narrower and more flexible, so it gets a narrower tyre as well.

Damon.

[clarion]

A couple of times I've run a larger tyre on the back than the front.  I've never done it the other way round, though the comfort argument seems reasonable enough.

Usually, I used the same, as I liked to swap them when part worn.

[mattc]

I actually have different sized rims front and back on one bike. The rear wheel always takes more hammer because of the dishing, so that benefits from being heavier, the front can be lighter, narrower and more flexible, so it gets a narrower tyre as well.

Now using a weedy front wheel makes sense to me. Does a lighter wheel = more comfort? The "unsprung weight" theory suggests so.

Maybe light front wheel + big front tyre = max comfort?

[Biggsy]

How much "comfort" can you get from a bike wheel?  I don't expect any at all from mine.

The front wheel can be lighter than the rear, if you like, because it takes less weight and isn't dished.  But you don't want it to be so weedy that it can't survive a pothole.

[border-rider]

Usually, I used the same, as I liked to swap them when part worn.

Mmm.

I'm not sure I'd want to swap them over since the back usually wears more and I prefer to have the roadholding at t front

Some people retire the back, put the front on the back and a new one on the front. Is that what you meant ?

Also - if you run *significantly* different sized tyres you can get quite different profiles and wear patterns.  Much weirdness might ensue if you swap them.

[Basil]

I've never understood the swapping tyres idea.  You still get the same amount of wear overall.

[clarion]

Usually, I used the same, as I liked to swap them when part worn.

Mmm.

I'm not sure I'd want to swap them over since the back usually wears more and I prefer to have the roadholding at t front

Some people retire the back, put the front on the back and a new one on the front. Is that what you meant ?

Also - if you run *significantly* different sized tyres you can get quite different profiles and wear patterns.  Much weirdness might ensue if you swap them.

^That^

[Greenbank]

I've never understood the swapping tyres idea.  You still get the same amount of wear overall.

Yes, but the idea is that you always have the tyre with most tread/grip on the front, and rear tyres wear faster than front tyres.

I have a 26mm Stradius Elite TG on the SON front just because it has lasted after I swapped to using 25mm GP 4 Seasons on all other wheels.