Author Topic: Rear tyre advice  (Read 1238 times)

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Offline ninja365

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Re: Rear tyre advice
Reply #20 on: January 13, 2021, 08:08:35 PM
*Originally Posted by Backtobikes [+]
Hey guys thanks for all your input much appreciated. Have e mailed the dealers waiting for a reply. The thing is whilst I've done nearly a thousand miles and the bike has handled like a dream now I know somethings not right I have that nagging doubt which I dont want when riding. So I will be changing the tyre to reccomended size whether it be at my cost or the dealers.

Okay, so someone else to wade in with another point of view.......

Tyre sizes are recommended to tyre manufacturers based on information from the bike manufacturer but are not mandatory..... With regard to the oversized 190/50 instead of a 180/55, the everyday rider may notice that the bike might turn in a little slower but have a bigger contact area. I picked up a ZXR750 back in the day from Bristol and rode it back home to near Norwich which had a 190/50 fitted instead of a 170/60!!. The bike was absolutely fine and seeing as money was tight back then it got ridden for a good few thousand miles before changing it. I did notice the turn in speed was much quicker after fitting the correct size and the back end was a bit higher.
Also had experience the other way on my ZX7R, standard fitment 190/50 and i went to a 180/55 to speed up turn in (and also added 10mm of ride height :007:), again no drama's, no omg moments from the tyres, just grip.

Bottom line from my opinion is although the tyre is a little oversized, it isn't dangerous. As you have stated, the bike runs fine and feels great. When you start dragging the pegs on the road and feel the back end losing grip then get it changed. If the dealer is happy to change it under due diligance then happy days, if not don't be frightened to ride it and just enjoy it.

Joe.

Offline tim.8061

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Re: Rear tyre advice
Reply #21 on: January 14, 2021, 11:51:08 AM
*Originally Posted by ninja365 [+]
With regard to the oversized 190/50 instead of a 180/55, the everyday rider may notice that the bike might turn in a little slower but have a bigger contact area.

Can you tell us your reliable source who says fitting a 190 tyre on a rim designed for a 180 gives a bigger contact patch or is this just "Dave on the internet" who is also an expert on covid vaccines?
Last Edit: January 14, 2021, 11:55:38 AM by tim.8061

Offline ninja365

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Re: Rear tyre advice
Reply #22 on: January 14, 2021, 12:39:50 PM
*Originally Posted by tim.8061 [+]
Can you tell us your reliable source who says fitting a 190 tyre on a rim designed for a 180 gives a bigger contact patch or is this just "Dave on the internet" who is also an expert on covid vaccines?

Hi Tim

I think possibly i've used the wrong word.  :430: I should have said wider and not bigger. A 190 section tyre is wider than a 180 therefore it will provide a wider area of contact.
Contact patch size can be changed by altering tyre pressures.

Offline tim.8061

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Re: Rear tyre advice
Reply #23 on: January 14, 2021, 01:18:13 PM
Wider/bigger -  now you're just fudging the words!

Again, what's your source? (I'm well aware 190 is a bigger number than 180 BTW.)

Offline ninja365

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Re: Rear tyre advice
Reply #24 on: January 14, 2021, 01:52:10 PM
*Originally Posted by tim.8061 [+]
Wider/bigger -  now you're just fudging the words!

Again, what's your source? (I'm well aware 190 is a bigger number than 180 BTW.)
[/quote

My source is a tape measure. A 190 section tyre is 190mm in width, a 180 section is 180mm in width. So therefore 190 will give you a wider contact area as its 10mm bigger

You seem to have gotten patch and area mixed up, i only spoke about area. In my world "patch" is the point the motorcyles's tyres make contact with road/track. "Area" is the amount of tyre available to make a patch.

Even with the right size of tyre, the contact PATCH can be altered by changing the pressures and this was picked up from a Dave Moss Tuning session and various track day instructors.   
 :763:



Offline tim.8061

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Re: Rear tyre advice
Reply #25 on: January 14, 2021, 02:39:55 PM
I completely agree 190mm is bigger than 180mm but you're confusing a linear dimension with a measurement of area which is in square millimetres, so invalid. Continental (not me btw) say if you pinch a 190 width tyre onto a rim meant for 180 then anything could happen. The radius of the 190 cross section is decreased, its surface curve where it hits the road is tighter so contact is decreased - not sure why you think that's better tbh. Unless you can quote a track day forum where ST riders all say they fit 190 tyres and go quicker I remain sceptical of your claims.

Offline ninja365

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Re: Rear tyre advice
Reply #26 on: January 14, 2021, 03:52:00 PM
*Originally Posted by tim.8061 [+]
I completely agree 190mm is bigger than 180mm but you're confusing a linear dimension with a measurement of area which is in square millimetres, so invalid. Continental (not me btw) say if you pinch a 190 width tyre onto a rim meant for 180 then anything could happen. The radius of the 190 cross section is decreased, its surface curve where it hits the road is tighter so contact is decreased - not sure why you think that's better tbh. Unless you can quote a track day forum where ST riders all say they fit 190 tyres and go quicker I remain sceptical of your claims.

Tim, i'm going to park this conversation as i feel you have completely misunderstood what both grv and me have said. Neither of us is saying its optimum to fit a 190 and nowhere did i state it was better, but it isn't dangerous either. I stand by what i have said as have personal experience of this.

I respect your opinion but don't agree.  Parked  :001:

Offline tim.8061

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Offline sabre

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Re: Rear tyre advice
Reply #28 on: January 15, 2021, 08:49:48 AM

I guess if nothing else BtB (the original poster) could wave this article in the face of his dealer to help him make his case for a replacement tyre?

Steve.
2013 Triumph Street Triple R
1989 Yamaha TDR250
recent departures: 2003 ZRX1200r + 2015 CRF250L :-(