Asymmetric front/rear tyres?

[mjr]

Is that because these are weights of the whole bike rather than per wheel in the other table?

it must be. The pressures are just ridiculous otherwise.

The pressures for 37mm tyres aren't good even so - IMO about right for the front but low enough for the back that I'd expect pinch punctures on the rear unless using a very stiff tyre.

[gbnz]

Vorpal thanks for the link. I found this as another positive reason (from Brucey):

Arguably when there is a slimy layer of crud on the road a (relatively) smaller contact patch at higher pressure will cut through it and find grip where a (relatively) larger contact patch at lower pressure won't.
I 've had many more front end slides on wide front tyres without much tread than I have narrower front tyres (which are run at higher pressure) and/or which have a more aggressive tread. Both features increase the contact pressure.

My Voyager Hypers are prone to slipping in the wet, so a narrower front tyre might be a good idea.

Hmm......I run the touring bike on 28mm front/32mm rear, never had an issue (Hit 40mph+ four weeks ago on a downhill stretch, on a bike fully loaded for camping).

But as an emergency measure on Sunday (Train to catch), swapped the 32 spoke/28mm tyre for a 32 spoke/25mm tyre from the flat bar road bike, prior to a 100+ mile ride (Wheel was buckled). The bike was fine on the flat, but at anything over 18-20mph it was extremely unstable - the front end of the bike was wobbling around, I actually felt it necessary to walk down two steep downhill stretches on the Dales.

The front tyre was a narrow road type tyre, but never had an issue when it's been on the flat bar road bike at 30mph where both tyres are 25mm

[Zanda]

Sheldon Brown tried mismatched tyre width and wrote it up. He advocated a front tyre narrower for lightweight. But he also tried it the other way round - the front tyre wider - which he thought was better for comfort, giving a little more front line suspension at the fork and more shock absorption to the handlebar.

https://www.sheldonbrown.com/tires.html#mixing

He doesn't discuss the effects of panniers weighing down the rear; perhaps in those circumstances a wide rear tyre is preferable.

[reohn2]

Sheldon Brown tried mismatched tyre width and wrote it up. He advocated a front tyre narrower for lightweight. But he also tried it the other way round - the front tyre wider - which he thought was better for comfort, giving a little more front line suspension at the fork and more shock absorption to the handlebar.

https://www.sheldonbrown.com/tires.html#mixing

He doesn't discuss the effects of panniers weighing down the rear; perhaps in those circumstances a wide rear tyre is preferable.

This gets worserer
If the front wider tyre was better,why didn't he advocate a wider tyre on the rear too,or would he then need to go even wider on the front to uneven things up?

[Zanda]

It's not a case of either set up being 'better', I imagine Sheldon would have replied, it depends whether you're trying to achieve comfort or speed. In essence, he suggested narrow front is fast (but less comfortable), whereas wide front is comfortable (but less fast). His reasons are here. I think this assumes a bike with little or no luggage, just the rider.

The comment about panniers was mine. Loading the rear carrier moves the centre of gravity backwards which ought to mean a fairly wide rear tyre, regardless of the front tyre width.

In the Sheldon Brown scheme, you could take relative tyre width out of the question, like this:

1. Find out which front tyre width allows you to avoid pinch flats, then add some width until your wrists are comfortable when you're riding.

2. Find out which rear tyre width allows you to avoid pinch flats.

I'd add:

3. Add some to (2) if you'll be riding with luggage on a rear rack.

4. Add some to (3) until your backside is comfortable when you're riding.

5. You now have your tyre widths. If front and rear are not equal, don't worry about it.

[reohn2]

It's not a case of either set up being 'better', I imagine Sheldon would have answered, it depends whether you're trying to achieve comfort or speed. In essence, he suggested narrow front is fast (but less comfortable), whereas wide front is comfortable (but less fast). His reasons are on the page I linked.

The comment about panniers was mine. Loading the rear carrier moves the centre of gravity backwards which ought to mean a fairly wide rear tyre, regardless of the front tyre width.

My reply was leettle tongue in cheek sorry if it didn't cone across as that.

My whole point in my posts throughout this thread is that other than clearance limitations there's no appreciable gain in having different tyre sizes front and back.Yes a bigger tyre on the front will be more comfortable but so will matching it up on the rear and speed loss is negligible if at all.
Bigger tyres don't necessarily mean slower averages,I've posted on the forum before that comfort toward the end of longer rides translates into more forward motion,because the rest of the body is relaxed and so isn't eating up energy,relaxed muscles don't need as much energy as tense,tired,stressed ones.

[Gattonero]

Does anyone use tyres of different widths at the front and rear?
There is generally more weight on the rear wheel: is this a reason to use a wider tyre at the rear?
Are there other reasons to have a wider rear tyre?
Conversely, are there reasons why this is not a good idea (other than just convention or convenience)?

Only in Mtb, often slightly bigger at the front for more grip: you never want to lose you front wheel.

On a road bike you ought to distribute the weight in the first place, though there will always be some more weight on the rear wheel, you want to reduce this as much as possible, both with the rider and the luggage.

[Roadster]

There's no appreciable gain in having different tyre sizes front and back.

Not only that, there are downsides as well. Two different sizes of tyre have to be bought and maintained as spares, and swapping them around can become needlessly inconvenient and/or problematical. Each size requires a different pressure depending not just on whether it's fitted to the front or rear, but also on whether it's wider or narrower than the one it replaces.
These "problems" are obviously not insurmountable but they are totally avoidable - why bother when we can have the simplicity of same sized tyres front and rear? One of the criticisms of the Raleigh Chopper was that it pretended to be something it wasn't, i.e. a motorbike, and putting tyres of different sizes on a bicycle panders to the same sensibility.

[blackbike]

I have a 25 mm tyre on the front wheel of one of my tourers and a 28 mm one on the back. I am using up the last 28mm tyre from my reserves as I now prefer 25mm tyres on my tourers and I won't be buying any more 28 mm tyres.

I haven't noticed any handling quirks due to the mismatch in sizes.

As for symmetry my bike is as symmetrical as it was when it had two equal size tyres on it as all my bikes only have one axis of symmetry which is a slice down the centre line like Damien Hirst's cow in formaldehyde.

[Tigerbiten]

There's no appreciable gain in having different tyre sizes front and back.

For me there is because I'm aiming for different properties front and back.
For my front tyres I want to have a low rolling resistance, while on my back tyre I want to have the maximum thickness of rubber.
So two different types of tyre tend to have different sizes, Marathon Supreme's 42-406 on the fronts/trailer for speed and a Big Apple 50-406 on the back for wear.
On the back of my bent trike I tended to wear a Supreme out in around 4k miles. While I now get roughly double that with a BA on the back.
Hence the difference ...........

As 406 Supremes are no longer made, I'm not sure if I'm going back to Racers or Tykers on the front/trailer, both are 40-406.
When I didn't aim for the different properties front/back then I had the same tyre all round, be it Racers, Tykers or Supremes.

[reohn2]

There's no appreciable gain in having different tyre sizes front and back.

For me there is because I'm aiming for different properties front and back.
For my front tyres I want to have a low rolling resistance, while on my back tyre I want to have the maximum thickness of rubber.
So two different types of tyre tend to have different sizes, Marathon Supreme's 42-406 on the fronts/trailer for speed and a Big Apple 50-406 on the back for wear.
On the back of my bent trike I tended to wear a Supreme out in around 4k miles. While I now get roughly double that with a BA on the back.
Hence the difference ...........

As 406 Supremes are no longer made, I'm not sure if I'm going back to Racers or Tykers on the front/trailer, both are 40-406.
When I didn't aim for the different properties front/back then I had the same tyre all round, be it Racers, Tykers or Supremes.

Perhaps things a different for trikes,not being a tricyclist I don't know,but generally I was confining my comments to upwrong,so I stand corrected

[Brucey]

the arguments that apply to trikes can equally well apply to upright bicycles as well. The loading of the front tyre is completely different to the loading of the rear tyre, so there is no particular reason to think that the same type of tyre is going to be optimal for both front and rear use; given that rears in matched sets usually wear about three times faster than fronts, it is obvious that any single type of tyre is going to be a compromise on one wheel or the other.

If you asked an experienced MTBer if it was 'best' to run the same tyre front and rear, they'd probably laugh.

The benefit of different tyres is that you can run a really nice tyre on the front, which is light, easy rolling, comfortable, and steers well, whilst having a robust long-wearing tyre on the rear.

The arguments concerning

a) spares and
b) tyre pressures

are specious; the optimum tyre pressures can be the same as one another if you choose your tyres carefully (which is surely an improvement as it is simpler) and any old tyre (of which you need only one) will do as a spare if needs must; no-one is advocating different rim sizes. OK, you might have to (briefly) put up with having the same tyre front and rear, but that is not the end of the world....

cheers

[reohn2]

For uprights I'll take same psi for different sized tyres front and rear, however the different sized tyres front and rear being optimum argument I won't,it doesn't stand up under experience or logic.

[Tigerbiten]

Perhaps things a different for trikes,not being a tricyclist I don't know,but generally I was confining my comments to upwrong,so I stand corrected

I would say for 99% of cyclist, the difference between the front and back tyres usage/wear/grip/etc is so small that the "one size fits all" works and is simple.
They find a tyre they like, fit it all around and forget about it.
It works and thats how I used to be.

It's the odd 1% of cyclist (MTB, tourers, trikes, etc) where running different tyres makes a big difference.
I only started after on one tour I wore out 2.5 back tyres in ~4,500 miles, one in under 1,000 miles going around Iceland, that I really started to run different front to back tyres.
As finding good 406 tyres on tour is more a matter of luck in what a bike shop is stocking, it makes a sense to me to go for a tyre which maximizes wear while keeping the fronts as low rolling resistance.
Since swapping to the Supremes/BA combo, I've done three 6k tours and only killed 1 back tyre vs three 4.5k tours and 4 dead back tyres where I had the same tyre all around.
I still carry a spare tyre but knowing I'll probably finish a tour with the same back tyre I started with helps ..........

[mjr]

The benefit of different tyres is that you can run a really nice tyre on the front, which is light, easy rolling, comfortable, and steers well, whilst having a robust long-wearing tyre on the rear.

I've reverted to having the same tyres front and rear because I like taking advantage of the "unnecessary" width on the front to run the tyre at a lower pressure and offer a comfier ride for the handlebars, while the saddle is comforted by springs anyway.