Going from a 21" to a 19" front tire, bad idea?????
CCjon
Posted 1/13/2016 10:10 PM (#87486)
Subject: Going from a 21" to a 19" front tire, bad idea?????



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Have been thinking about this and wanted to get thoughts, comments  and feedback from the collective wisdom here.

Have a KLR650 rig with three different size tires: 17" on the rear, 21" on the front and a 19" on the sidecar.  Am carrying a fully mounted spare 17" rear tire. That leaves the front and sidecar with no backup, two different sizes and no way to swap back and forth to get the most mileage out of each. 

The OEM front tire is a 90/90-21. The sidecar tire is a 110/90-19. 

What would be the pros and cons of having the front tire relaced with a 19" rim, and run a 110/90-19 tire up front, same as the sidecar tire? 

Would this reduce trail and make steering easier? Not that steering is stiff now, but....   

 Could I go with a fatter front tire? What benefits would that have?

 If this makes sense to do, who do recommend to do the lacing and any particular size/width rim? 

If you think this is a dumb idea, say so and why. 

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fastjoe
Posted 1/14/2016 12:07 AM (#87489 - in reply to #87486)
Subject: RE: Going from a 21" to a 19" front tire, bad idea?????



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You can use this calculator to compare the size of the tires:

https://www.tacomaworld.com/tirecalc?tires=90-90r21-110-90r19
It's what I use when I am trying to figure this kind of stuff out.

I don't believe you will be able to feel a 2.5% drop in diameter, but I am no expert. Jay or Lonnie would be the guys to ask.
It should take some trail away and improve the handling if anything being a slightly smaller diameter.

Edited by fastjoe 1/14/2016 12:11 AM
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Hack'n
Posted 1/14/2016 12:54 PM (#87497 - in reply to #87486)
Subject: Re: Going from a 21" to a 19" front tire, bad idea?????



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Slight loss in ground clearance, slight increase in braking, slightly quicker steering and probably longer life front tire.

Lonnie
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Claus
Posted 1/15/2016 3:21 AM (#87502 - in reply to #87486)
Subject: Re: Going from a 21" to a 19" front tire, bad idea?????


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It is like Lonnie says.Not much different but in the favourable direction.
As long as your rig has the same hubs and brakedisc on front- and sidecarwheel it really would be an option if you like to carry a spare wheel.
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CCjon
Posted 1/17/2016 6:11 AM (#87519 - in reply to #87486)
Subject: Re: Going from a 21" to a 19" front tire, bad idea?????



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Thanks for the input, all sounds positive. Now to get prices on a 19" rim and relacing.
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SwampFox
Posted 1/17/2016 8:37 AM (#87520 - in reply to #87519)
Subject: Re: Going from a 21" to a 19" front tire, bad idea?????



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I recall Gravel Guy up in Central Texas had favorable results with a 19" front wheel on his KLR/Velorex rig.  This combination is no longer together, but here's a pic from 2013:

 

There's some discussion here:  http://www.sidecar.com/mbbs22/forums/thread-view.asp?tid=10795&...

 

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CCjon
Posted 1/17/2016 9:00 AM (#87521 - in reply to #87486)
Subject: Re: Going from a 21" to a 19" front tire, bad idea?????



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Some great photos there Lee, thank you.

That was a fun weekend in Milam too.
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JustKip
Posted 2/14/2016 3:56 PM (#87906 - in reply to #87486)
Subject: Re: Going from a 21" to a 19" front tire, bad idea?????



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So I'm a little late to the party...just signed up today.

IMO, you will need a spare wheel that you can attach either the front OR sidecar rotor to. Typically the front brake will be the biggest, and the one to the side will be smallest, unless you're using a proportioning valve and a shared master cylinder (I speculate). This is what Ural is doing with their "universal spare" on the 3-disc '14 and newer rigs. You bolt on the disc from the wheel being replaced.

I'm considering going with 18" wheels all the way around on my F800GSA, and it's going to take some head scratching and cash to make it happen.
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