If I've been running two different size tyres the larger has always gone on the front (conventional wisdom, I believe) – does anybody run them the other way round, and why?

I swapped some tyres over this morning and accidentally did this- is it worth bothering about swapping them back in a hurry?

I used to do that, had a spesh chunder 2.35 on the back, and a spesh enduro 2.2 on the front. Great fun. Very grippy for technical climbs as well.

Yes – Hardtail has a 2.35 Larsen on the rear and a 2.1 Ignitor on the front.
Fat rear tyre gives an extra degree of comfort (the Larsen is brilliant for this). Comfort not needed on the front as there's 130mm forks for that.

Be interested to know why I "should" be running them any other way…

I've always gone bigger on the front with the logic that correcting the rear end is doable, if you lose the front end you're often toast. So I tend to run whatever size I feel I need up front and then the smallest/fastest I can get away with out back…

I can't think what the pros of running bigger on the back would be…

lol – ok, HT makes sense I guess, but even on my HT I still run bigger at the front…

Be interested to know why I "should" be running them any other way…

More grip on the front/less chance of washing out.

More grip on the front/less chance of washing out

More grip from a fatter tyre? Depends on the tread surely?

fatter tyre doesn't mean more grip.

i run 2.35 highrolller up front and 2.4 advantage on the back. the difference in reality is more than .05".

this is on a HT. find i have more grip on the ups over roots/rocks and have – touch wood – not pinch flatted.

Dez – My 2.35 Nevs are grippier than the 2.1s I also have…

I don't think people are saying bigger always = grippier but generally the same tred in a bigger size has more grip.

Actually the bigger carcass is likely to be more stable over rough terrain anyway so less skittish…

For what it's worth I'm currently running a 2.35 Blue Groove and 2.1 Small Block 8 – crazy fun!

This is exactly the type of trainspotterish topic that keeps me awake at night. Big days out in the Spanish mountains coming up in Sep, have just replaced my (front) BlueGroove 2.1 and Nobby Nic 2.25 snakeskin with new ones. Going on a Ti hardtail, penny dropping the Nic should really be on the front for super extra grip, back end can (usually) worry about itself.

I generally go for as big as possible without getting silly heavy. On my heckler I got a huuuuuge (well for a non DH tyre) enduro 2.3 on the back, smaller minion ST 2.3 front.
Enduro is a big volume tyre to try to prevent pinch punctures without too much of a weight penalty.
Minion sticks like poo to a blanket, could try a 2.5 but might be a bit too heavy.
Just what I've ended up with but it works well for me. Normally use bigger rear tyre on HTs too. I think the norm for a slightly bigger front tyre is sensible but there are so many other factors, just go with what works for you.

I can't think what the pros of running bigger on the back would be…

comfort, less damage to tyre and rim.

Yeah but if you go any bigger than 2.1 on the back and you're not gravity riding, you're probably punishing yourself way more energy wise than any comfort gains…

And also, damage to tyre and rim – what kind of riding you talking about here, I'd assume 'most' riders are on a 2.1 at least and even clanging about on my Five, my uber skinny, not-really-a-2.1-are-they High Rollers have never been at risk damaging the rim or tyre…

Even if you were on a hardcore hardtail and your riding was extreme enough to warrant a 2.4 or something out back, chances are your riding is hardcore enough to warrant a 2.4 up front too!

I noticed some bikes in a bike shop the other day, Commencals, I think, with Larsens on the back and fat High Rollers on the front. Looked a bit weird.
Does it come from DHing then – this odd idea that you don't need as much grip on the rear?

FWIW I've always run the same tyres f&r on my full sus.

Well it's ultimately a compromise, stick a fast tyre on the back for speed and to save weight and to try and kill some drag – the offset is that you've got to try and not bin it. Luckily, the rear is easier to save if it does go whereas the front is often terminal if it goes – which is why a lot of riders only put something silly on the rear.

Obviously really good riders will get away with silly tyres front and rear – I've got mates who run 2.1 Small Block 8s front and rear and always thrash me to the bottom LOL

It's also a tactic for encouraging drifting and can be quite fun… 🙂

Yeah but if you go any bigger than 2.1 on the back and you're not gravity riding, you're probably punishing yourself way more energy wise than any comfort gains…

depends how (un)fit you are, some uf us aren't worried about effort 😉

And also, damage to tyre and rim – what kind of riding you talking about here, I'd assume 'most' riders are on a 2.1 at least and even clanging about on my Five, my uber skinny, not-really-a-2.1-are-they High Rollers have never been at risk damaging the rim or tyre…

Very happy that your 5" bike has never been near damaging the rim on <2.1 tyre. My experience is not the same. Perhaps you are riding gaily on poofter trails? 😉

On a HT you are more likely to pinch flat or dent the rim at the rear rather than the front, going over rocks etc. Rear tyre has much more effect on comfort also. You seem to be starting from the position that the front tyre MUST be the same as the rear. Why?

2.5" Nevegal on the front, 2.35" highroller on the back of my hardtail.

2" Marathon on the front, 2.5" Hookworm on the back of the Big Dummy. That's all about added cush for the passenger though. 😀

Predates DH by a long way, BMX's always had biger front tires

Advantages –
+ more comfort through the wrists
+ better braking performance
+ better cornering

I run 2.35 High Roller up front and 2.4 hollyroler out back on a hardtail. Tread pattern, or lack of it, has a much bigger (-ve) effect than tire size or weight on rolling resitance. Mine climbs liek a giant anthem! Theres jst enough give in a 2.4 to mean climbing realy is a case of point at the line you want and spin.

Usualy i'd run the same tire F+R, but its good to experiemnt occasianlay, especialy when the results are this good! 😀

Wot Cynic al says. Its a bit "old skool" now but still valid in some conditions. If grip is not the limiting factor but comfort and pinch flats are – big tyre on the back. If grip is the limiting factor big tyre on the front.

When decent sus forks started arriving some folk took this as an opportunity to reduce the size of the front tyre and it did not need so much shock absorbtion

cynic-al – the winks don't make you any less of a bitch!

I'm only making observations here and discussing the topic – why are you so bent out of shape?

(For what it's worth, I ride a HT too and run the same tyres across both bikes)

cynic al is not just a bitch – he is the bitch and soon to be my bitch 😈

Jeez I am just having a bit of fun with it, where's the sense of humour?