Street tire on KS18XL (Metzeler Sportec 70/90 R14)

[digithom]

Hi all,

I want to share my experience on test of a street tire on my KS18XL.
Since my use of this euc is 95% on road I wanted to try a street tire in oreder to maximize grip and linearity on riding, my sensation on riding this euc with stock tire is that I can feel the transition from central thread of the tire and the side where the tire is softly knobbed, the idea is to have a tire with a flat behaviour from straight position to carve position.

The choice is not so big and I decided for a Metzeler Sportec, it was a good tire when I used it on my motorbike and, compared with competitors (Michelin and Brighestone) it is available with a lower load index, that should result in a softer tire and more comfortable on riding, and even more, i like it's design 
The nearest size to the stock 18x2.5" is the 70/90R14, it should be only a little bit wider, but small enough to fit on ks18

I received it and the first impression was "it is really huge", it is 80mm wide while it should be 70mm

 

this size will never fit in ks18xl, then I realized that the rim will squeeze the tire and also reduce the width, this was confirmed by clamping by hand on the rim side, also the total width was reduced to the expeced size 

So, I decided to proceed and after a lot of pain, for mounting a tubeless tire using only screwdrivers a got the result.

at the end, the 40mm rim, squeezed the tire more than I could do by hand, and the finale width i 65mm, almost the same of the 2.5" stock tire

it is time to test ...
even if I was not fine, I did a tour of my street, and the first impressione is, it is completely unusable 
even more, the tire is so soft that every small stone stick on the tire and sometimes I have the impression that it is no easy for the wheel to eject it, but, it is night, I'm tired, and tomorrow I'll spend more time on tuning ...

Edited January 5, 2022 by digithom
missing tire size

[Paradox]

Wow after all that work you find the tire unusable.  I hope that you can "break" it in.  Maybe it just needs a little use.  Good luck!

[digithom]

today I had more time and energy to do a wider test ...
Again, yesterday I was tired, but this wheel keeps to be undriveable, I feel like if I've never used an euc, I'm no longer able to do the basic things nor mantain a straight position, the wheel keeps going where the street has a small inclination and follow every crack in the ground.
It is very very nimble, too much, every correction even if minimal result in a excess and near a loss of control.

I took all I need to change pressure on the fly and did a bigger tour

Started with 1.9 bar (29psi) and reduced to 1.5 (21psi), keeping in mind that I was riding the old tire at 1.6, a little bit better, but not yet a good change respect the stock tire.
At the end I decided to put it very low, just to understand if this is the right direction, and deflated to 1.1bar ... the miracle ... it started to behave much similar to the stock, and I feel now I need to learn

it still runs harder than the stock, so, I could deflate it more, but I think it is better to learn a bit before, it is now usable and I can ride more or less normally 

 

 

[Gaman]

Seems like a crazy low pressure, basically a little above the environment pressure so all the structural rigidity is coming from the rubber itself?

[enaon]

41 minutes ago, Gaman said:

Seems like a crazy low pressure, basically a little above the environment pressure so all the structural rigidity is coming from the rubber itself?

yes, the sportec has very strong sidewalls. I think it is only suitable for suspension wheels, the s18 maybe. 

Edited January 6, 2022 by enaon

[Planemo]

1 hour ago, Gaman said:

Seems like a crazy low pressure, basically a little above the environment pressure so all the structural rigidity is coming from the rubber itself?

No it's not. It's still 1.1 bar above ambient pressure.

I'm not surprised it rides badly. I had the same issue fitting an 80 section Pilot to an MSX. The narrow rim squeezed the tyre so much that the profile went completely tits up and it gave all sorts of handling traits. Not to mention the stiffness removed all compliance, even down at 17psi. I took it straight off.

 Tyres are designed to run at, or near to, the width of rim they are designed for. And I'm still not convinced that stiff, tubeless MC tyres are great for EUC's without suspension.

[digithom]

3 hours ago, Gaman said:

Seems like a crazy low pressure, basically a little above the environment pressure so all the structural rigidity is coming from the rubber itself?

 

2 hours ago, enaon said:

yes, the sportec has very strong sidewalls. I think it is only suitable for suspension wheels, the s18 maybe. 

Yes, sportec has very strong sidewalls, but 1 bar is not enviromental pressure.
The pressure reported by pressure indicatore is meant as relative to enviromental, so, when we have 0 bar it is completely deflated (the same as enviromental) but at 1 bar we have 1 bar above enviromentale pressure.

 

[enaon]

correct, sorry, I was just commenting on the sidewalls on the sportec. I have it on the s18, it is indeed very stiff on the sides, very soft material on the contact area, but very stiff overall, not suitable for non suspension I think. 

Edited January 6, 2022 by enaon

[digithom]

1 hour ago, Planemo said:

No it's not. It's still 1.1 bar above ambient pressure.

I'm not surprised it rides badly. I had the same issue fitting an 80 section Pilot to an MSX. The narrow rim squeezed the tyre so much that the profile went completely tits up and it gave all sorts of handling traits. Not to mention the stiffness removed all compliance, even down at 17psi. I took it straight off.

 Tyres are designed to run at, or near to, the width of rim they are designed for. And I'm still not convinced that stiff, tubeless MC tyres are great for EUC's without suspension.

I completely agree with you, the rim width squeezes the tyre, in fact, the tread width is 65mm instead the 70mm declared.
This also affects the shape of the tread, the radius became lower and this is the rason it follows road inclinatio and you need to reduce drastically the pressure so that the tyre flattens and show an apparente bigger radius.
But this is a workaround, we simply need a wider rim.

[enaon]

why did you try the metzeler on the xl in the first place, was it curiosity? Have you tried any other bike tires?

Edited January 6, 2022 by enaon

[Planemo]

2 minutes ago, digithom said:

But this is a workaround, we simply need a wider rim.

I would suggest that rather than a wider rim, a tyre of the correct width would be better in all situations. I know it's very tempting to go wider (I am one of those people) but in reality it just doesn't work. Same with cars, motorbikes, anything really. As for grip, you only have to look at how skinny the racing 125cc MC tyres were, compared to say the 500cc class. The 125's really didn't struggle for grip so it goes to show that with the right tyre and more specifically the right size, a lot of grip can be found.

[digithom]

Today it is rainy, but yesterday I've ran about 30km in two rounds ...
The first interesring aspect is that the tire warms up, like a bike tire 

(I apologize for the nose of my dog on the right of the picture )

this is the 38 celsius after some km, the tread became more soft and it behaves nicely.

After 20-25km I felt so brave to speed up a little bit and I noticed that from 30 to 40 kph a vibration apperas on pedals.
The pro is that this gives me a sort of "aptic feedback" about the speed, the con is vibrations are not good: vibrations, noise and temperature, requires energy to be produced and for shure, this is affecting the range of the euc.
I suspect vibration are given by those longitudinal thread on tire design that, on rotating of the wheel, hits the ground in a rapid sequence, causing the vibration I'm describing.
I tested the tire centering by lifting up the euc and letting the wheel spin, and it doesn't vibrates, it spinsa like a disc without the minimal vibration, so, it is for shure a ground contact issue.

Doing this test, I also seen the tire increasing external radius, under the effect of the centrifugal force, i think, too much for the 50kph it was spinning, the tire is given to work up to 150kph ...
I think this is a conseguence of the low pressure, tire is not rigid as it should and changes it's shape too easily.

Edited January 6, 2022 by digithom

[Planemo]

I suspect that virtually all of the heat generated will be due to the extremely low pressure you are running. I guess if you were brave enough, run it at the pressure stated on the tyre wall and probe it again.

[digithom]

25 minutes ago, enaon said:

why did you try the metzeler on the xl in the first place, was it curiosity? Have you tried any other bike tires?

Yes, just curiosity.
I thinks that ks18xl is a street euc, it's appearence, it's elegance, you can ride it in an offroad environment sometimes, but if you plan to offroad frequently this is not the euc for you, this is my opinion and so, since my use is 95% on road I tried to definitely specialize it for street.
This is the first bike tire I try, cencerning the vibration issue described on the other post, if I'm right about the reason of the vibration, maybe that Bridgestone Battlax whould have been a better choice.

Look at the left one on the photo, it is the front type, the only one avalible on the size 70/90,  it doesn't have those longitudinal cuts as Metzeler, and should solve the vibration issue.
But I couldn't realize this before this test 

 

Edited January 6, 2022 by digithom

[digithom]

30 minutes ago, Planemo said:

I would suggest that rather than a wider rim, a tyre of the correct width would be better in all situations. I know it's very tempting to go wider (I am one of those people) but in reality it just doesn't work. Same with cars, motorbikes, anything really. As for grip, you only have to look at how skinny the racing 125cc MC tyres were, compared to say the 500cc class. The 125's really didn't struggle for grip so it goes to show that with the right tyre and more specifically the right size, a lot of grip can be found.

I was not searching for a wide as possible tire but just was intrested to test a street tire, and this is the smallest availble in the market.
I again agree with you, but I mean that a tire projected to be 70mm and that shows 65mm bacause of the wrong rim is not working properly, so, first of all you need the right rim (wider in this case) in order to be able to evaluate correctly the tire.
If I could find a street treaded specific euc tire, of the standard 18x2,5 size, I whould have preferred it for shure, but I didn't find any so I told myself "let's give a try to this and let's make this experience, it will cost only 25€, even if I'll fail, it is a low price to learn so much things"
Maybe at the end I'll rever to to the stock tire, but before, I'll keep 200-300km to test and try whatevere I can.

Edited January 6, 2022 by digithom

[Planemo]

What you have to consider in your quest is that MC street tyres are generally designed to be 'less bulbous' than bicycle tyres. Consider a mountain bike for example where the tyre may be 2.8" (7.1cm) but the rim is only 30mm (1.2"). This works OK because bicycles don't need a lot of sidewall strength, so it gets traded for bump absorption and pinch flat protection due to profile height. 

So now for example we take an MSX rim which is also 30mm internal width and we try to fit an 80 width (around 3") MC tyre on it but the MC tyre isn't designed for a 30mm width rim. In fact the absolute minimum recommended rim width for an 80 is 1.6" (40mm) and ideally it should be 1.85" (47mm). So now we can see that whilst bicycle tyres give us a little freedom in terms of rim size they are fitted to, proper MC stuff doesn't as it's designed quite specifically for rim width. And you and I have seen first hand how badly it can affect tyre profile once you start squeezing those beads together to enable fitment to a 30mm rim (the 18XL may be even less - I don't know).

And none of the above even touches on the stiffness increase when using MC tyres.

I admire your attempt though, I did the same thing. And I would love a decent MC tyre to work given how much better they are, particularly re puncture protection. But that protection comes at a cost - stiffness. Which is why, for the moment, I have stock with the stock knobby on the Sherman which has a deep tread (to reduce the chance of punctures) but also has reasonable bicycle-like compliance.

[Funky]

Some post mentioned: Michelin CITY PRO 70/90 R14 

Same size as Metzeler Sportec 70/90 R14

It was on MSP doh.. And he loved it. (Maybe different rubber compound or something.. I don't know, but i was planning getting it for mine 18xl)

Maybe because it's tubed version?

18xl rim width is 40mm (outside)

Check @DjPanJan Post for more info. >>>

Michelin CITY PRO - Video

 

 

Edited January 6, 2022 by Funky

[digithom]

Some other info over this tire ...
I forgot to mention the weight, the stock is 800gr less than the Sportec

 vs

 

Last detail, the height from rim to ground is 50mm, so very similar to the stock one.

 

 

[digithom]

5 hours ago, Planemo said:

What you have to consider in your quest is that MC street tyres are generally designed to be 'less bulbous' than bicycle tyres. Consider a mountain bike for example where the tyre may be 2.8" (7.1cm) but the rim is only 30mm (1.2"). This works OK because bicycles don't need a lot of sidewall strength, so it gets traded for bump absorption and pinch flat protection due to profile height. 

So now for example we take an MSX rim which is also 30mm internal width and we try to fit an 80 width (around 3") MC tyre on it but the MC tyre isn't designed for a 30mm width rim. In fact the absolute minimum recommended rim width for an 80 is 1.6" (40mm) and ideally it should be 1.85" (47mm). So now we can see that whilst bicycle tyres give us a little freedom in terms of rim size they are fitted to, proper MC stuff doesn't as it's designed quite specifically for rim width. And you and I have seen first hand how badly it can affect tyre profile once you start squeezing those beads together to enable fitment to a 30mm rim (the 18XL may be even less - I don't know).

And none of the above even touches on the stiffness increase when using MC tyres.

I admire your attempt though, I did the same thing. And I would love a decent MC tyre to work given how much better they are, particularly re puncture protection. But that protection comes at a cost - stiffness. Which is why, for the moment, I have stock with the stock knobby on the Sherman which has a deep tread (to reduce the chance of punctures) but also has reasonable bicycle-like compliance.

You have been crystal clear about theory on rims and sizes and doing this small experience I can only confirm this.
Moreover, even if we could have the right rim for this tire, it will result in a too hard tire and the right combination will be fouund only in a too low tire pressure.
Up to now, I can't really say that I made an upgrade, and I can't suggest to others to do the same thing.
I'll ride this tire anyway for a bit, to see how much my confidence will make the difference.
 

[digithom]

3 hours ago, Funky said:

Some post mentioned: Michelin CITY PRO 70/90 R14 

Same size as Metzeler Sportec 70/90 R14

It was on MSP doh.. And he loved it. (Maybe different rubber compound or something.. I don't know, but i was planning getting it for mine 18xl)

Maybe because it's tubed version?

18xl rim width is 40mm (outside)

 

As told even from @Planemo the main problem is that the rim is not wide enough to let the tire section take his right radius.
Even if the Michelin is a tubed type, look at the video and carefully watch the width of every scooter shown, they are not comparable to the 18xl rim width ...
Just for start, it would be interesting to know if the mounted tire on the rim, reports a 70mm wide or less, this is the first symptom that the rim is too narrow even for this tire.
I think the result will be more or less the same as the Metzeler.
The user who loved it, also admits to be a non expert user, and when we really would like to have a success after a hard job, it is easy to don't be able to admit that "it is not better than the stock" 
Anyway, if you're an expert rider, it will be a pleasure if you try and report us your opinion.

[digithom]

a small video showing the Metzeler Sportec hardness even at 1.1bar (16psi) ...
My weight is 67kg, let's say 70-72kg including helmet, jacket, ecc ...

 

[Funky]

Hmm, same thing could be told about all "these" motocross, scooter tires then.

Which almost everyone puts on s18, most gotway's, any wheel which can mount 18x3 tires.

Example: Heidenau K66 (One of the tires i was looking at..) there are 80/80-14 and 80/90-14 size. On rim it's width is 73-76mm (also 40mm rim)

And most love it, and swear to god it's best tire. xD

Ofc you changed something.. It's the "new" feeling maybe.  Gotta test it for myself, and see what you're talking about.

[digithom]

Today it was sunny, so, why not run more km on the new tire ? 

I have to admit that the confidence make a big difference, the more km I ride the more I feel confident with my "new" EUC.
I rised the pressure from 1.1 to 1.3 (19PSI), wheel is really nimble but now I can manage it and it is going to be funny, even this vibration at 30km/h is a lot reduced, and slowly disappears increasing the speed, I'm able now to run at top speed, this was really scary just one day ago.
I'm going to appreciate this tire and this only after 50km so, definitely, I think I can give a realistic and objective response only after 200-300km.

Another aspect of the behaviour is given by the increased weight of the rotating mass that is now 800gr. more.
More precisely I'm talking about the gyroscopic precession phonomenon involved on the wheel, I try to explain ...
Easily speaking, in a rotating disc, every transversal force applyed, is traslated by 90degrees in the rotation direction, applyed on our EUC, this means that if you try to incline the euc pulling it with your leg, it is like if you're applying this force in the front (90 degrees forward in the rotating direction), with the result that it will turn: pulling with left leg, it will turn right.
Knowing this, when you're carving, for example in a long trafic roundabout, and you're slightly touching the frame with the leg, if the street is no flat, the oscillation of your body will result in "pulses" of the leg in the frame that will produces pulses of steereing: wobble.
The good news is that, the wheel is not wobbling itself, but you're make it wobble.
The euc must be ridden hardly, you can't sligthly touch the frame with the leg, instead, you musth strongly push with the leg.
It is a completely different way to ride, it is like to have bought a new euc, not only a new tire, riding must be more physic.
I'm going to love it 

If I could change something, I would like to try the Bridgestone Battlax, I'm shure that with it runs smother than the Metzelere because of it's different design in the thread.

 

Edited January 7, 2022 by digithom

[Funky]

6 minutes ago, digithom said:

Today it was sunny, so, why not run more km on the new tire ? 

I have to admit that the confidence make a big difference, the more km I ride the more I feel confident with my "new" EUC.
I rised the pressure from 1.1 to 1.3 (19PSI), wheel is really nimble but now I can manage it and it is going to be funny, even this vibration at 30km/h is a lot reduced, and slowly disappears increasing the speed, I'm able now to run at top speed, this was really scary just one day ago.
I'm going to appreciate this tire and this only after 50km so, definitely, I think I can give a realistic and objective response only after 200-300km.

Another aspect of the behaviour is given by the increased weight of the rotating mass that is now 800gr. more.
More precisely I'm talking about the gyroscopic precession phonomenon involved on the wheel, I try to explain ...
Easily speaking, in a rotating disc, every transversal force applyed, is traslated by 90degrees in the rotation direction, applyed on our EUC, this means that if you try to incline the euc pulling it with your leg, it is like if you're applying this force in the front (90 degrees forward in the rotating direction), with the result that it will turn: pulling with left leg, it will turn right.
Knowing this, when you're carving, for example in a long trafic roundabout, and you're slightly touching the frame with the leg, if the street is no flat, the oscillation of your body will result in "pulses" of the leg in the frame that will produces pulses of steereing: wobble.
The good news is that, the wheel is not wobbling itself, but you're make it wobble.
The euc must be ridden hardly, you can't sligthly touch the frame with the leg, instead, you musth strongly push with the leg.
It is a completely different way to ride, it is like to have bought a new euc, not only a new tire, riding must be more physic.
I'm going to love it 

If I could change something, I would like to try the Bridgestone Battlax, I'm shure that with it runs smother than the Metzelere because of it's different design in the thread.

 

If you want to try different tire try City Pro that i mentioned. xD

It has that center grove vs that solid middle you got now. Also being tubed version it should handle differently.

Keep us updated. <3 Like i was saying, new tire = change everything. Hope you will enjoy the "New" wheel.

[digithom]

16 hours ago, Funky said:

If you want to try different tire try City Pro that i mentioned. xD

It has that center grove vs that solid middle you got now. Also being tubed version it should handle differently.

Keep us updated. <3 Like i was saying, new tire = change everything. Hope you will enjoy the "New" wheel.

To be honest, the main reason I've not bought the Michelin is I don't like it's tread pattern, I know this shouldn't keept in consideration but this is, and I don't want another middle choice like the stock but some meant for a specific use. 

In the idea to waste money I'll give a try to the Battlax, not to the Michelin. 

But now it's your time 😁

What will you test? 😀