"Squaring Off" rear Tourance

[Invicta Moto]

Just got back from about 2400 miles across Europe. I checked the tyres before setting off and they seemed to have plenty of life for the length of trip.... Two up and luggage on board seems to have knocked the shit out of them though!

I ran at standard book pressures and wound up the preload a bit to cope with Mrs D and her luggage and now I have a rear Tourance that looks like the centre has been planed off. Mind you, there's still tread to about 3mm depth right in the centre…

There was quite a bit of motorway plugging to get across to Brno and on the last day to kill off 400 miles of France. I began to notice the handling was affected at lower speeds expecially when in slow turns as it seems the bikes had to get off the flat-spot onto the the edges and it was more pronounced as it did so....? On the m-way it made no difference!

Is this something I should have been expecting? I've never noticed anything like it before on other bikes, although they have worn (obviously!) more generally.

 

[BarcodeMan]

Hi IM,

Certainly your experience supports what I've noticed, particularly when loaded up. I also run standard pressures and adjust as recommended when loaded / 2-up.

I decided to run with the flat profile for one more trip up to Scotland recently just to get my money's worth and to be honest didn't really suffer too badly even once up into the twisty stuff.

Had new Tourance rear fitted last week though and the low speed handling is noticeably improved.

 

[snodog]

me too

I've just replaced my rear Tourance due to squaring it off.
The Aberdonian in me wasn't happy seeing as there seemed to be loads (its all relative) of tread left on the tyre. But it had "shoulders" and leaning it over at roundabouts etc at slow speed was a bit scary - one minute its upright, the next, it seems to drop for miles.

Still, I got 7 500 miles out of it.

 

[Spanish Bob]

mine lasted 9000kms but were illegal. they square off quite quickly if they get much motorway or heavy loads. Mine didnt have that lovely falling off a cliff face effect in corners, as they had also done lots of twisties, but still I was quite surprised.

 

[Invicta Moto]

Thanks.

Praise be! It's the worst wear I have seen in such a short mileage trip for years but I am still glad that it's not uncommon!

Total mileage on this set is about 8500 to date and the front looks pretty much okay but the "kryton's" head effect may force a change before too long. I noticed it when turning into a parking space and such like manoeuvres.... the sudden drop to one side... not fun with passenger and luggage...

Thanks for your comments guys.

 

[Bramble]

It's just the same with Anakees - they seem to square off suddenly on the M-way then whoooa as you drooooooooooop into the first post-squared-off bend - but (happily they're still sticky). New rear tomorrow from Tony Salt.

 

[(RIP) Geriatric Germ]

A matter of Woads

Since I've lived and rid in The Welcome Of Wales, Read cameras and Cops, but wonderful bendy wodes, and bikes that love to corner and squirt out of bends, bejesus my tyres (Bridgestone ) manage around 3,500 miles before being well scuffed all over. But with roads? that can scare me witless at 15% over legal, the engoyment is worth the cost and faith in the grip of trailwings on the GSA and the B20's on the now departed K12LTSE. If yer tires are ''Square'' go faster round bends Get more messy pants per mile wear yer boots out, scare oncoming traffic and Live a Little

 

[AZDrifterus]

Metzler recommends pressures of 36 and 42 PSI front and rear.
This is way above BMW's "2-up" presssures.
Higher pressures might reduce center-tread wear.
I just swapped Tourances for Trailwings last weekend.
So far, the Tourances seem to resist off-center steering inputs - and then require more lean angle, especially at slow speeds.
Will I get used to this?
Is this how the bike is supposed to handle?

 

[deefa]

i would have thought that higher pressures would increase centre wear not reduce it, anyone know for sure ?

 

[Invicta Moto]

i would have thought that higher pressures would increase centre wear not reduce it, anyone know for sure ?

I would have thought so too as the tyre would be more rounded off on the profile.

I have always tended to run tyres at the tyre manufacturers recommended pressures rather than the bike makers recommendation, I may be wrong, but the bike's handbook may not cover the same tyre?

I had 41.5psi in the rear when I checked it again after noticing the wear pattern.

I tried to photogtraph it but it hasn't come out that well! But the light grey colour marks the extent of the centre flatspot!

 

[(RIP) Kaister]

Higher pressures 'should' stop the tyre deforming at the contact patch and creating heat build up.
ideally - the contact patch should be the same regardless of loads and speed , - pressure changes will help achieve this.

more heat = softer = more wear.

also lower pressures allow tyrewall flex in a lateral motion = ie allowing the wheel rim to move sideways relative to the contact patch - gives that 'wallowy' feel.

Also (again ) - as the tyre wears out it has less rigidity and flexs and deforms more.

Increasing pressure v. v. gradually and linearly over the life of the tyre negates all the above.

new tyre ( rear ) = ( say ) 36psi / 42psi
old tyre (rear ) about to be changed = 48psi / 50psi

Next time you change tyres, feel the difference between the old and the new tyre stiffness.

Thats why - if you don't inrease tyre pressures on old tyres they feel really bad.
If you've got a worn tyre- more thah 3/4 worn - raise the pressure above 42psi and see if you can 'feel' it.

 

[Deleted account W]

i would have thought that higher pressures would increase centre wear not reduce it, anyone know for sure ?

If you run with higher pressure on a rounded profile tyre, less of the central area of the tyre will be in contact with the road when cornering. With a lower pressure the central part of the tyre that receives the most wear when riding, still has contact with the road and as such suffers even more wear when cornering. My take on the problem looking at it logically.

 

[MikeO]

If you've got a worn tyre- more thah 3/4 worn - raise the pressure above 42psi and see if you can 'feel' it.

The maximum pressure - stamped into the sidewall of the Tourance I've just had fitted - is 42psi. I'd personally be unhappy exceeding the manufacturer's design maximum...

Mike

ps Drifterus, I think you'll find 36/42 is exactly what BMW recommend for 2 up load/speed

 

[MikeO]

By the way - THIS is a squared off rear Tourance

(still fitted to the wheel & inflated)...

Mike

 

[(RIP) Kaister]

pretty much all manufacturers say 36/42 as hi-speed or 2 up these days.

...and its 70 on the m-way speed limit as well.

if you don't try anything - you'll never find out ??

 

[MikeO]

pretty much all manufacturers say 36/42 as hi-speed or 2 up these days.

...and its 70 on the m-way speed limit as well.

if you don't try anything - you'll never find out ??

The 70 limit isn't a design limit - over inflating a tyre isn't something I'm willing to do - I'll happily 'never find out'...

Mike

 

[Invicta Moto]

By the way - THIS is a squared off rear Tourance

(still fitted to the wheel & inflated)...

Mike

Mine innt that far off when you take the carpet from under it.....

 

[AZDrifterus]

MikeO

Metzler's recomendation of 36/42 is for solo riding.
I was trying to offer an analogy to auto tires - underinflation = center tread wear.

Sorry I missed you in Phoenix.