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View Full Version : Do faster bikes go round corners quicker due to fatter tyres?


monkey
26-09-07, 10:46 PM
No mickey taking please. On track for example, will an R1 be able to take the same corner as an R6 quicker due to the tyres having more surface area on the track?
:)

Lissa
26-09-07, 10:49 PM
I was always of the understanding that fatter tyres meant slower cornering. I thought that was why some R1 riders we know have changed the 190 rear for a 180...............to quicken up the steering.

ASM-Forever
26-09-07, 10:49 PM
What a ridiculous question....we all know R6 riders are far superior/faster than R1 riders :)

monkey
26-09-07, 10:53 PM
I was always of the understanding that fatter tyres meant slower cornering. I thought that was why some R1 riders we know have changed the 190 rear for a 180...............to quicken up the steering.

Wouldn't that be to get it to turn in quicker?

Lissa
26-09-07, 10:55 PM
Wouldn't that be to get it to turn in quicker?

Yes, and therefore wouldn't it take the corner quicker, theoretically?

Devine
26-09-07, 11:45 PM
corner speed would not matter either size will corner at the same speed....

its the turning in that speeds up, the transition from side to side is quicker with thin tyres

monkey
26-09-07, 11:59 PM
I mean are they capable of it rather than do they and I don't mean corners so long that they do it on power.

davidimurray
27-09-07, 07:41 AM
I would have thought that the contact patch size of the tyre with the tarmac is the critical factor. This would be affected by tyre width, profile and the load on the tyre.

Pedrosa
27-09-07, 07:48 AM
Wider tyre only means that a little more rider input would be needed to get the bike to lean in. Much of that though is negated by the "quick" steering geometry of many bikes.

SV650Racer
27-09-07, 08:47 AM
A race setup BSB bike running a 200 section rear will turn as quickly as a BSB125 GP bike. BUT although the BSB bike will have more side grip than the 125..it will actually be the 125 in skinny tyres that will corner quicker.

Its all down to lots of things...too much to explain really.

Putting a bigger tyre on your bike is not worth it IMHO and can slow the steering slightly on the road. On track a 600 can run a 180 or 190..but you do have to set them up differently.

riktherider
27-09-07, 09:13 AM
weight of the bike, centre of mass, suspension set up, distribution of weight etc etc all make up the most important factors. the rs 125 and 250's are very very light, and there centre of gravity is very low so they can corner a lot faster than a heavier bike such as an r1 which has its centre of gravity heigher up. tyres do have a huge affect on cornering speeds and turn in speeds, but not as much as your general set up.

muffles
27-09-07, 11:42 AM
Assuming the same bike, but tested with different tyres, my knowledge of physics would seem to indicate that the tyre that has the steepest angle at it's edge would take the corner quickest.

Again this assumes all else is the same, which clearly it isn't - one big one being grip. I am also assuming the same turn in speed, which although it is part of "taking a corner", seems to be not part of the discussion here.

Grip is a weird one too, and if the laws of physics apply in the same way to motorcycle tyres as they do to car tyres, then the contact patch area thing has an interesting point people often overlook (not saying anyone has here btw!). That point is that the contact patch area is the same regardless of tyre width/size, assuming all else is equal. It's because the contact patch area is directly related to the air pressure inside the tyre. What changes about the contact patch is the shape of the contact patch, when you change tyre size/width.

This is really coming from numerous discussions with car folk on forums, that believe that a wider tyre offers more grip purely because it is wider. It may offer more grip, but that's down to something else - different pressure, different tyre compound, etc.

monkey
27-09-07, 01:19 PM
That all makes sense Muffles. It's got to ultimately be down to lean angle as lean angle and speed are proportionate and I guess tyre profile denotes that.

Devine
27-09-07, 01:31 PM
As i already said.... thiner tyres make for quicker steering in like for like tests....

same bike
same setup
same make of tyre

its the flickable ness that you lose with wider tyres.

Stop thinking of it as 1 corner and think of it as a lap, depending on how many corners of track it was you could go round faster with smaller width tyres. the benifits of smaller width really come into play with supermoto type tracks

But its all depending on the track as to whats best, some might even favour a slightly wider tyre if its a less twisty faster type track.

But theres no getting away from FATTER tyres look nicer though :)

plowsie
27-09-07, 01:39 PM
Nope HTH

stuartyboy
27-09-07, 02:33 PM
General rule of thumb is if you up your tyre size you slow down the turn/steering. Just about every mag, forum, armchair expert all say the same thing.

Bike(?) magazine did a pullout for all the tyres sizes, profiles, rubbers etc. There's a section about why changing to a wider tyres lessens the contact patch and slows the steering. See if I can dig it out and post it up here.

plowsie
27-09-07, 04:11 PM
Only reason i know is cos i've got a 180/55 rear on mine.