Tyre sizes

booldawg

In general is it better to run the same tyre widths front and back? I've seen several bike with wider at the front. What benefit would this have and how would the bike handle if I went wider at the back?

MacAndCheese

booldawg wrote:

In general is it better to run the same tyre widths front and back? I've seen several bike with wider at the front. What benefit would this have and how would the bike handle if I went wider at the back?

As a rule, most people prefer more grip on front as they'd rather have the back sliding out (front wheel slides aren't much fun!)

dan shard

I recently had a similar dilema. Opted for very fat and nobbly on the front and back

(2.4 Schwalbe fat albert) Very glad I did, the grip is brilliant and I can pump them up hard so rolling resistance is actualy better than my previous 2.25 racing ralph which I had to run at low pressure to get any form of grip

Northwind

Sometimes it works, sometimes not. Remember the 2 tyres are doing 2 different jobs so there's some good reasons to mix sizes, compounds, pressures, even makes and brands. A great front tyre isn't always a good back tyre.

psymon

just bought a pair of Advantages 2.25 front 2.1 rear.

this will be the first time ive had none matching sizes so im interested to see how it goes.

vanamees

dan shard wrote:

I recently had a similar dilema. Opted for very fat and nobbly on the front and back

(2.4 Schwalbe fat albert) Very glad I did, the grip is brilliant and I can pump them up hard so rolling resistance is actualy better than my previous 2.25 racing ralph which I had to run at low pressure to get any form of grip

Offroad high pressure = high rolling resistance, low pressure = low rolling resistance.

booldawg

Thanks all. I hired a bike out at GT that ran a wider tyre up front and it felt really positive and grippy around the trial. Wondered if it was down to the tyre config.? Couldve been loads of other factors though.

robertpb

dan shard wrote:

I recently had a similar dilema. Opted for very fat and nobbly on the front and back

(2.4 Schwalbe fat albert) Very glad I did, the grip is brilliant and I can pump them up hard so rolling resistance is actualy better than my previous 2.25 racing ralph which I had to run at low pressure to get any form of grip

That's like comparing a tractor tyre to a F1 tyre, both brilliant at what they do but can't do the other ones job.

As already pointed out high pressure, high rolling resistance, in my tyres low pressure is 20psi and high 26psi.

bennett_346

vanamees wrote:

dan shard wrote:

I recently had a similar dilema. Opted for very fat and nobbly on the front and back

(2.4 Schwalbe fat albert) Very glad I did, the grip is brilliant and I can pump them up hard so rolling resistance is actualy better than my previous 2.25 racing ralph which I had to run at low pressure to get any form of grip

Offroad high pressure = high rolling resistance, low pressure = low rolling resistance.

:roll:

Thats the most vague statement ive ever seen.

Raymondavalon

I tend to run the same width tyres on both ends of my All Mountain bike, but when entering an event a few years back I did notice a lot of riders running skinnier tyres on the back end.
I may give this a try on the hardtail one fine day to see if it does make a marked difference

timpop

I'll throw this in again. I love my tires. I am running the newish Panaracer Cerdric Gracia 4X/AM 2.35 on the front and the XC 2.1 on the back.
The 2.1 is a climbing demon, I've found it really grippy and responsive.
The larger, more knobbly front is great around the trails, sticky and quick.
Loads of confidence riding this set-up. It's nice having the rear a bit lighter, I find it really improves the handling. Both tires corner fantastically.
They're not cheap but are well worth it.

http://www.bikeradar.com/mtb/news/artic ... yres-24700

.blitz

I never really thought about running the same size tyres f & r :? They both have different jobs to do so why would they be the same?

Apart from the good advice offered above, there is also the consideration that the rear wheel is the heaviest component on a mountain bike and absolutely the last place to add any more weight or friction in the form of a big, lardy, grippy tyre.

The front tyre tends to clear a path for the rear anyway, so all it has to do is transfer the full awesomeness of one's legs and do a bit of menial braking now and then. The front is where it's all at - get that sorted and the rear will follow.

PXR5

I was also going to post on this one, I can sort of understand the reasoning behind the idea of bigger on the front so the back slides first...but what i can't get my head around is that in my youf i had a number of rather large motorcycles, and never ever was the tyre on the front end close to the size of the back....now i know the wheels/rims aren't the same size and all that, but there is a logic there somewhere...yes i know all the drive goes through the back, but isn't this the same on your bike ???
Again if you fitted a racing tyre on your motorbike the softer compound went straight on the back to give maximum grip and drive, never on the front to reduce the chance of wash out..

For what its worth i'm currently running maxxis ADvantage 2.1s front and back...

getonyourbike

PXR5 wrote:

I was also going to post on this one, I can sort of understand the reasoning behind the idea of bigger on the front so the back slides first...but what i can't get my head around is that in my youf i had a number of rather large motorcycles, and never ever was the tyre on the front end close to the size of the back....now i know the wheels/rims aren't the same size and all that, but there is a logic there somewhere...yes i know all the drive goes through the back, but isn't this the same on your bike ???
Again if you fitted a racing tyre on your motorbike the softer compound went straight on the back to give maximum grip and drive, never on the front to reduce the chance of wash out..

For what its worth i'm currently running maxxis ADvantage 2.1s front and back...

i GUESS that its because if you don't have ab ig tyre on the back of a motorcycle you won't be able to get the power down, it will just slip, not grip. Its quite hard on a MTB to spin the rear wheel when accelerating so it isn't such a priority to have losts of grip on the back.

Shiney Napper

My Stumpy Fsr came with a 2.2 on the front and a 2.0 on the rear. I took the front tyre off and replaced with a 2.0 my theory was it would be harder to push the fatter tyre through the mud etc???

vanamees writes Offroad high pressure = high rolling resistance, low pressure = low rolling resistance.

Is that right, what sort of pressures should you run?

vanamees

Shiney Napper wrote:

My Stumpy Fsr came with a 2.2 on the front and a 2.0 on the rear. I took the front tyre off and replaced with a 2.0 my theory was it would be harder to push the fatter tyre through the mud etc???

vanamees writes Offroad high pressure = high rolling resistance, low pressure = low rolling resistance.

Is that right, what sort of pressures should you run?

I ride 28 . 30 psi. High pressure works only on road. Read f/e Schwalbe test
results. Google will find more.

weescott

The front wheel steers, the rear follows. If the rear slips out momentum will correct it. If the front slips out. It's one tatty over the side!

I run a 2.4" Schwalbe NN up front and a 2.4" MK rear. The NN is a bigger tyre. >insert HF here<

torgey33

Going on about tyre pressures, some quotes 28-30 psi, others even lower, is it right to run these kind of pressures on a slim tyre like a MudX (2.0), or can you only get away with it on fatter rubber.

robertpb

I'm running 24psi in my Mud X rear and 22psi in a Trailracker on the front.

Keith Bontrager said he thought my pressures were low, but he rides 29psi, then he's heavier than me.

supersonic

You can't just keep reducing pressure and keep reducing rolling resistance. The Schwalbe stuff is more about that the ideal pressure for rolling resistance on different surfaces is often less than you might think.

torgey33

robertpb wrote:

I'm running 24psi in my Mud X rear and 22psi in a Trailracker on the front.

Keith Bontrager said he thought my pressures were low, but he rides 29psi, then he's heavier than me.

Are you running tubeless ?

Northwind

The different tyre sizes on motorbikes are just down to the differences in performance- if you could put 180hhp down through your mtb rear tyre, well, you'd explode the wheel A cyclist can put more braking force on the front wheel than they can put pedalling force on the rear wheel.

But it's very complicated. The front wheel on maximum braking is generating more force than the rear wheel on maximum power, but it's also getting massively loaded up by the weight transferwhich itself generates more grip. Of course the rear gets loaded on acceleration but not to the same extent.

And of course you might well be trying to put down a lot of those horses on a corner exit while leaned over but you'll never, never want to put down that much braking force while leaned over.

Also the profile of the steering tyre has a more profound effect on turning action than the profile of the following tyre so the fatness of the rear is less of a disadvantage. Ride a fat-fronted german-style streetfighter and see how it turns, horrible.

So again it comes back to the different ends doing different jobs.

Also, if we're honest with ourselves fat motorbike tyres are a lot about fashion. Modern 160/60s have much more grip than 190/50s from a few years ago but they don't look manly enough

robertpb

torgey33 wrote:

robertpb wrote:

I'm running 24psi in my Mud X rear and 22psi in a Trailracker on the front.

Keith Bontrager said he thought my pressures were low, but he rides 29psi, then he's heavier than me.

Are you running tubeless ?

Not at all

robertpb

To add to what Northwind has posted most off road motorbikes have a larger rimmed taller and narrower tyre on the front, with a smaller rimmed wider lower profile tyre out back.

There isn't a great deal of difference in the amount of tyre on the ground, but the tread will be different to get the best out of two different jobs.

PXR5

@ Northwind

Thanks for that explanation, it makes sense, its just that empirically what i've seen most people do is the opposite to the bigger front than back arguement.

Most guys here are running tubless set up, and we all run around 2-2.5 Bar pressure (28-35 Psi), as soon as someone feels there bike is a bit sluggish or not rolling well the first reaction is to pump up a bit the front tyre, this wil reduce contact area pressure, which is pretty much equivalent to fitting a smaller tyre, similarly if anyone is having trouble with grip on climbs its time to let out a bit of pressure from the rear tyre, down below 2 Bar, again increasing contact area equivalent to fitting a bigger tyre.

Think it'll stay a mystery as there are so many parameters, i'm sure for example that my 85kg on 14kg rigid backend bike needs a different tyre set up to my mates 65kg on his 10kg full susser.

Just as an aside if i win the lottery i'm buying one of these, won't be the first on my list, but its got a 240/40R18 rear :shock: :shock: :shock:

http://suzukimotorcycle.co.in/VZR1800/i ... paper4.jpg