Understanding Downhill Tyres

mbuk is da bestmbuk is da best Posts: 121
edited June 2014 in Downhill, freeride and 4X
The more I ride it, the more i get into downhill. I was just wondering what size tires and what pressures do you want for different conditions also is do you always want a tacky compound?


[Mod] The Mod would like to point out that "tires" is spelt 'tyres' Hopefully the posts below should help a lot of people get thier heads round the masses of downhill tyres out there. [/mod]
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  • Dirt_MonkeyDirt_Monkey Posts: 9,184
    pressure depends entirely on the rim, tyre, tube and conditions. size of the tyre depends on conditions, but for this time of the year id use a 2.3 rear 2.5 front if i could afford to. tacky=more grip generally, but wear out much quicker


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  • Sir HCSir HC Posts: 20,148
    A stickier compound tyre will grip more.


    Quick run through of Tyres and there uses:

    Dry - Maxxis Minion, Michelin Comp 24, Comp 32
    Dry/intermediate - High roller, Comp 16
    Intermediate - Maxxis Swampthing
    Wet - Wet Scream, Mud 3


    Tyre size is dependant on Weight, conditions.

    For example: I'm running 2.5 High Roller 42a Front and rear. I'm quite a heavy rider and like to run my tyres at lower pressures than most.

    It is suggested that smaller riders run a smaller tyre, and larger riders run bigger tyres.

    You always run either same sized tyres front and rear, or a smaller rear tyre. This ensures that the bike is theoretically balanced front to rear, or the rear will break away first, which is easier to control, compared to the front breaking way.


    Another one is tread direction, all tyres have a rotational direction. You also get tyres that are Front/Rear specific. The front tyre is designed to corner and brake, and the rear is designed to put down traction, breaking and cornering.
    With tyres such as the High roller, IRC Kujo, etc, some people turn the rear tyre around to give more traction when braking.

    Yet more confusion, some people mix and match tyres to change the grip balance the bike. For example, a maxxis high roller on the front, minion on the rear, i have used this set up, work very well in dry to intermediate conditions.
    A grippier tyre is always used up front, a few combinations:
    front/rear
    High Roller/Minion R
    Swampthing/High roller
    Wet Scream/Swampthing
    Comp 16/ Comp 24


    A pair of Dual Ply, 42a compound, 2.35 or 2.5, Maxxis High rollers will cope in almost all conditions.
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  • AlexAlex Posts: 2,224
    Tyre choice is an artform. Maxxis' tyre range is the easiest to understand though.

    Tyre type:

    Deep thick shitty mud: Wet Scream, Thin tyre with huge spikey knobbles that digs into the poo to give you grip, it's thin to give you mud clearance.

    Slime and thick mud: Swampthing, a tyre with high profile, widely spaced knobbles, use the thinnnest that is safe to use given your weight and the course.

    Wet conditions, loose stuff over harpack: Highroller, the do everything tyre. It's quicker than the swampy or wet scream and will do the job if the surface is loose or if you've got a wet surface without significant mud.

    Bone dry hardpack and rocks: Minions, Much quicker than any of the others because of lower rolling resistance. Only useful if there's no mud though.

    Tyre Width

    You need to match tyre width to conditions, tyre, tyre compound, rider weight, course type and bike.

    A wide tyre will give you more grip if the surface isn't thick mud. A wide tyre also allows you to run lower pressures giving still more grip. A wide tyre also protects your rims from roots and rocks.
    A thin tyre is much faster than a thick one due to the much lower rolling resistance and the fact that they're simply lighter. They are much more vulnerable to being overcome by rocks and roots and your weight, so you need to run a higher pressure in them (incidentaly, reducing rolling resistance still further).

    If you're after going fast, fit a thin tyre, if you want to survive (for example at Ft bill or in France) then get a thick tyre.

    Compound
    It's a dark art that only proffesional race mechanics understand. Someday they will reveal thier secrets....


    Not really, it's dead simple.

    put simply, you've got three compounds with maxxis.

    Slow-reezay 40a, which is mega mega soft, and expensive.
    Super-tacky 42a, which is still pretty soft, but not quite as steep
    Maxxpro which is about 60a Oh yeah, they're dirt cheap and have a red stripe too.

    The slow reezays and supertackys being mega soft work miracles on rocks and roots. They grip whee you would have never thought grip was available. Go to a race with slippy roots or rocks in without soft comound tyres on and you can forget finishing, let alone doing well.

    The maxxpros are gods gift to the budget racer though, fit some of these and you've got them for a year or so, so long as you keep them off the road. They simply don't wear anything like as fast as the others. They don't grip damp roots or rocks though, so not really a bringewood or caersws tyre. I use a set of maxxpro highrollers myself for practice on the local course.

    Soft compound tyres have a high rolling resistance, so if you go for supertacky or slow-reezay, make sure you get a thin tyre to make up for it. Likewise, hard compounds offer a lower rolling resistance, so you can afford to have a bigger one. You'll see lots of big, harder compound tyres at Ft Bill and in france, mostly because people are going to be dragging the brakes a lot, meaning soft compounds would wear too fast.

    Pressure

    Dead easy. Find a nice healthy balence for yourself on your local track. If you're short on grip, let a little out, if you're hitting the rims, put some more in. Big tyres require less pressure, little tyres require more, and so on.

    Balence all that out and you should know what you want.

    I have three sets:

    Maxxpro Highrollers in 2.5"
    Supertacky Highrollers in 2.35"
    Supertacky Swampthings in 2.3"

    They pretty much cover all eventualities for my small and spindly body. If you're a bigger chap, get some bigger tyres, unless it's muddy of course.

    Don't ask me about what compound you should use for wet screams, no-one knows, should you use hard compound to stop the knobs folding? Or soft so you grip the roots inbetween? It's confusing!



    When it's you out there, in the air, no-one cares, only the ground.
  • Crazy Dave CCrazy Dave C Posts: 7,615
    I generally put in as little as the course I am riding will let me away without puncturing, usually around the 20psi mark, with about 3psi or so difference between the front and the rear, the front being the softer tyre.


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  • Sir HCSir HC Posts: 20,148
    If you tend to lock your rear wheel a lot, run a harder rear tyre, otherwise you'll ruin the tyre.

    If you choose Maxxis, get the dual ply's. Also invest in some decent tubes, Maxxis, Hutchinson (my choice), IRC all make some excellent tubes. They'll pretty much remove the chance of punctures.

    Rim choice is also a factor in tyre width, if you've got wide rims, say a mavic EX729, D321, Doublewide. You should choose a wider tyre, to keep the tyre profile round, as this will keep the tyre at its optimum shape.
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  • AlexAlex Posts: 2,224
    You can't get the proper (named) maxxis tyres without dual plys, so i'm taking that as given.

    As for rims, best just choose a proper 21mm wide world beating rim in the first place [:D]



    When it's you out there, in the air, no-one cares, only the ground.
  • TomTom Posts: 5,945
    tyres: alex's pet love.

    MORE HARDCORE THAN YOUR MOM
  • AlexAlex Posts: 2,224
    Shhh. Tyre pimping is cheaper than fork pimping....



    When it's you out there, in the air, no-one cares, only the ground.
  • SavSav Posts: 17
    quote:Originally posted by Chasealex

    Tyre choice is an artform. Maxxis' tyre range is the easiest to understand though.

    Tyre type:

    Deep thick shitty mud: Swampthing, Thin tyre with huge spikey knobbles that digs into the poo to give you grip, it's thin to give you mud clearance.

    Slime and thick mud: Swampthing, a tyre with high profile, widely spaced knobbles, use the thinnnest that is safe to use given your weight and the course.




    wet scream is the mud tyre, not swampthing.

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  • Sir HCSir HC Posts: 20,148
    Swampthing

    Wet Scream

    Sav, Depends what type of mud though.
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  • SavSav Posts: 17
    this is very true mate...
    i was led to believe that the wet scream was for that real deep thick sh*tty mud,the sort that'd suck your wellies off![;)]
    was just pointin out in chasealexs post that the wet scream would be better for deep thick sludge.
    confusing though,if you went by the names you'd think they were meant for each others use...if that makes sense.

    My Bicycle
  • Sir HCSir HC Posts: 20,148
    See what you mean.

    The Swampthings are a mud tyre, but will cope with intermediate conditions as well. Wet screams are for when its real deep mud.



    Intense Socom
    Inbred
  • AlexAlex Posts: 2,224
    The Wet Scream is for when you've got deep wet muddy conditions all the way down. The Swampthing is for when you've got a layer of mud over hardish ground or varying conditions all the way down the trail for which a deep mud tyre would give poor performance.

    Both are Mud tyres. You've got to make the judgement on which to run.



    When it's you out there, in the air, no-one cares, only the ground.
  • ecsrobinecsrobin Posts: 0
    i love tyre pressures, spent all the porc weekender 2 years ago adjusting and playing not sure if the rest of the MBUK team were so keen :D



  • Sir HCSir HC Posts: 20,148
    It has to be done.

    I spent a whole day pissing around with my bike making sure everything is just so.



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  • 360360 Posts: 5,940
    further to whats already been said...

    360s tyre wisdom:

    further general rules

    1. Bigger tyre on the front, or same size f&r, quite simply you want more grip on the front wheel, its what you initiate a turn with. If the back end starts to go on a corner you can usually save if it , if the front end goes you've probably had it. Unfortunatley for those big hit owners out there this makes things more awkward but MMA are now doing a wider range of maxxis 24 tyres.

    2.Pressure, i run pretty much 30psi everywhere no matter what im doing, sure if you run less pressure you get more grip however at 20psi or so its very inconsistent because theres no longer enough pressure to support the carcass properly, the tyre can start to tuck under and all sorts. Secondly rolling resistance , with soft tyres you might be able to pin a couple of corners tighter and save a few tenths but with harder tyres your gonna roll faster over the whole course.

    things to think about:

    1. wide tyres are for bad riders, well ok thats abit of a generalisation but hear me out...
    take a maxxis tyre in 2.35 and 2.7 both will have almost exactly the same size side knobs and thats what your cornering on, sure your gonna get a slightly larger tyre footprint on the 2.7 but the difference is nothing compared to the masssively lower rolling resistance on a 2.35.
    So why bother with big tyres at all? thin tyres deflect easily , if you clip the edge of a rock its gonna send you off line, a big tyre wont do that so much. you also get much better straight line braking with a big tyre.

    So if you can hit your lines spot on and you dont need to brake to much then a smaller tyre is for you. But if riding through a 6inch gap at 30mph presents problems then fatter tyres are the one.

    2. compound chances are spending lots of money on supertacky or slow reezay tyres wont do much for you. sure stick on on the front where its gonna last but bung a maxxpro on the back and save some cash rather than 0.25secs.



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  • vanbobvanbob Posts: 3,025
    Ok. I need new tyres. I was going to get High Rollers in 2.35. However I'm stuck into which one I should buy. I basically do all sorts of riding - mainly jumping, street but I do some downhill and the odd bit of XC. I was thinking 60a, but I'm not 100% sure. Just some verification would do.


    vanbob
    the bum
  • Sir HCSir HC Posts: 20,148
    60a in 2.35, dual ply, and some maxxis/hutchinson dh tubes

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  • vanbobvanbob Posts: 3,025
    Are Panaracer Fire DH Pros any good? - ie. are they better than High Rollers.


    vanbob
    the bum
  • AlexAlex Posts: 2,224
    Nope, theyre utter 20p for the swearbox on anything but loam.



    When it's you out there, in the air, no-one cares, only the ground.
  • SpudMasterSpudMaster Posts: 1,143
    Looking for some High Roller UST but cant seem to find them in stock anywhere, other than in single ply and œ40 each at bike dock [:(]

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  • In these nice summer months I have been running a set of Maxxis High Rollers in a 60a compound . They`ve done about 6 circuits on the Marin Trail in Gwydir forest over the last few weeks until I had a strange occurrence . I was replacing a spoke on the Rear of my Patriot and I had a REAL TIMMEEEH! moment . For some reason I put the tyres on the wrong way around on the rear . I was going around Gwydir again and was having bags of fun and really hammering the Downhill sections `til we got to the bottom and a friend asked me why my tyre was in the wrong rotation . Since then I have also turned the front around and I still feel safe and planted . Basically once you have found a tyre you are happy with have a go at different configurations . The main part is to find the right tyre for you and the right kind of setup will naturally follow suit .

    I`ve spent quite a few years riding motorcycles and have allways taken a vested interest on what is keeping me upright . A tyre that gives you confidence in your braking and cornering will allow you to be a lot more happier and enjoy your riding . You`ll know when you have achieved this after a good day out and you realise you were Hammering and were in control without having to think about it . At the end of the day there will be advice that EVERYONE agrees with but there is also a LOT of advice that people will disagree on , take what is said to you on advisement and give it a whirl .... you have nothing to lose but your skin , confidence , kneecaps , teeth , expensive bike bits ....... just kidding ;ª)

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  • konaguy49konaguy49 Posts: 1,722
    tyre choice as these guys is pretty important, tyre pressuse is less specific, its to do with rider weight, i heavier rider will pinch easier so higher preasures but the extra weight will compress the tyre so a good amount of tread is always down, a lighter rider will run lower preasure, but the compound of the tyre makes a difference to the preasure you run them at, the best way to find out is buy a tire to suit the condition you ride in and adjust the preasure as you go

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  • Sir HCSir HC Posts: 20,148
    Tyre pressure is a balance between a few factors.

    Grip, the lower the pressure the higher the grip.

    Sidewall support, if you have too lower pressure you'll find the tyres fold under cornering/jumping.

    Rolling resistance, the higher the pressure, the faster the tyre will roll.


    Then you have to factor in you.
    Your weight, heavier people will need to run higher pressures as they transmit more force into the tyres.

    Suspension travel, longer travel bikes will let you run lower pressures, as less forces are transmitted from the rider to the tyres. Opposite with hardtails and short travel bikes.

    Your riding style, pinch flatting often and suchlike







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  • Super helpful!

    Whats MMA?

    If you die riding, you die happy
  • Sir HCSir HC Posts: 20,148
    MMA distribute MAxxis tyres.

    Raleigh also distribute Maxxis tyres.







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  • thanks

    What about the medusa tyre?
    Or the minion?


    Can you get the wet scream in 24?

    Has anyone ever put a wet scream on the front and a swamp thing on the back? If so what was it like?



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  • Sir HCSir HC Posts: 20,148
    quote:Originally posted by Big Drop

    thanks

    What about the medusa tyre?
    Or the minion?


    Can you get the wet scream in 24?

    Has anyone ever put a wet scream on the front and a swamp thing on the back? If so what was it like?



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    Read the whole topic again, and all your questions will be answered.







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