Tyre wave pattern

**Gixxer 4 ever** · 30th January 2006, 16:40

Can anyone help with this.
I have a 190 50 17 Diablo on a 1996 GSX-R 750V. If you sit on the floor behind the bike you see a wave pattern on the side of the tyres. Not chicken strips. The tyre is heavily scuffed to the very edge but there is a wave pattern around the edge of the tyre where the chicken strips could be.
They start at the out side edge of the tyre and move in to the tyre 3 mm over a distance of 27 mm. Then they tapper off back to the edge of the tyre and again that distance is 27 mm. Then there is a gap of 40 mm with normal scuffing from the road and then the next wave starts the same as the one described. This is even and travels completely around the tyre.
Same on the right hand side but the wave is only 2mm deep. Could the difference be due to road camber?
But my question is...does anyone know why this pattern has developed? It is only there after very hard throttle use out of corners. Could it be the tyre pressure is to soft? I run it at 38 psi cold. No pillion. Is the tyre crimping under load and hence the pattern?
The last tyre was a pilot sport and it did the same.
Any ideas?

**Two Smoker** · 30th January 2006, 16:53

any chance of a photo???

**onearmedbandit** · 30th January 2006, 16:54

Someone with the correct knowledge will be able to confirm this but after talking to a fellow member here it was pointed out to me that the tyre pressures my have been too low. Same thing happened on my 750 under hard throttle out of corners.

Just setup a temp. seat bump for the thou so over the next few nights I'll be trying to see if that does as well!! Better be careful with that right hand out of corners though!

**Gixxer 4 ever** · 30th January 2006, 17:04

Originally Posted by Two Smoker

any chance of a photo???

I will get the cam tomorrow and see if I can get pic's. Thanks for the help so far people.

**Motu** · 30th January 2006, 19:03

Cupping - check out the front tyre of a road ridden dirt bike with knobs,they all do it.

**Gixxer 4 ever** · 30th January 2006, 20:49

Originally Posted by Motu

Cupping - check out the front tyre of a road ridden dirt bike with knobs,they all do it.

Cool That would happen because of the movement in the knobs so there for it would indicate the tyre pressure is to low. Might have a play with it and see what comes up.

**Gixxer 4 ever** · 30th January 2006, 20:54

Originally Posted by Two Smoker

any chance of a photo???

Now you strike me as someone that knows a bit about bikes, so what would you think it could be. I tried to photograph it tonight but hard to get so will put it out in the sun tomorrow.
What pressure would you expect to run a rear, one up at? cold

**Sensei** · 30th January 2006, 21:08

I use 36-38 cold on the rear & 34-36 cold in the front , have used these for over 20 years on the road & have find them to be excellent .

**R1madness** · 31st January 2006, 08:08

It is a simple suspension adjustment problem combined with an incorrect tyre size. Sounds like you need some more rear preload. Is it squatting a lot at the rear under hard acceleration? Oh yea try the 180 as well because i think you are running on 5.5inch rear rim and the 190 is designed for a 6inch rim. You will get more rubber on the road with the right size tyre for the rim. The pressure sounds ok.

**Gixxer 4 ever** · 31st January 2006, 12:44

Originally Posted by Two Smoker

any chance of a photo???

Here it is

**Gixxer 4 ever** · 31st January 2006, 12:55

Originally Posted by R1madness

It is a simple suspension adjustment problem combined with an incorrect tyre size. Sounds like you need some more rear preload. Is it squatting a lot at the rear under hard acceleration? Oh yea try the 180 as well because i think you are running on 5.5inch rear rim and the 190 is designed for a 6inch rim. You will get more rubber on the road with the right size tyre for the rim. The pressure sounds ok.

Thanks for the reply.
It sits down and pulls the weight off the front under load, that's for sure. I road in the 7000 plus rev rang on the weekend when this happened and it really sits down and feels good. I will try a bit harder preload. Could well help but it never bogs down just sits down and gives you that "give me more" feeling I can do this. Good idea thanks

The bike is designed for the 190. Everything I have read said they are made for the 190 and I am sure the 180 will have far less tyre on the road than this 190 at any point in a corner. Could be wrong but I will stick to the 190.

Thanks for your help R1

**TwoSeven** · 31st January 2006, 16:58

Originally Posted by R1madness

It is a simple suspension adjustment problem combined with an incorrect tyre size. Sounds like you need some more rear preload. Is it squatting a lot at the rear under hard acceleration? Oh yea try the 180 as well because i think you are running on 5.5inch rear rim and the 190 is designed for a 6inch rim. You will get more rubber on the road with the right size tyre for the rim. The pressure sounds ok.

That doesnt at all sound right.

Can you explain the logic further ? - the math would be good

How does preload affect uneven tire wear ?

How does a bike squat under acceleration ?

**Two Smoker** · 31st January 2006, 17:11

Ive got the same problem on my ZXR400... This is due to the rear shock being too soft, and as R1Madness suggested, try upping the preload by 1/2 a turn on the rear shock see how it goes then...

**Gixxer 4 ever** · 31st January 2006, 22:30

Originally Posted by TwoSeven

That doesnt at all sound right.

Can you explain the logic further ? - the math would be good

How does preload affect uneven tire wear ?

How does a bike squat under acceleration ?

When I go into a corner, on a piece of road I know, I can keep the reves up and as I open the throttle just before the apex the front unloads the weight and that give the bike a real feeling of sitting the back down. But it is not an unstable or bounce it is a firmness that really gives you a good sling shot out of the corners. So I would describe it as "squatting". As long as the power stays on the rear unloads nice and evenly as you get out of the corner.
I am no racer and would only be a mid rang rider so I can only describe things as I see them. Or in this case feel them. I was interested to know why this Patten had developed and if someone suggests something that sounds like it might work I am happy to play with it and see. All part of the learning. If by tweaking the rear shock I get a better ride or foot print I am happy to try it.
Can't do any maths but I will soon know if the pattern disappears.

**Gixxer 4 ever** · 31st January 2006, 22:36

Originally Posted by Two Smoker

Ive got the same problem on my ZXR400... This is due to the rear shock being too soft, and as R1Madness suggested, try upping the preload by 1/2 a turn on the rear shock see how it goes then...

Thanks for the tip. I will try it over the weekend and report back.