Tires

[fredintoon]

Thank you all for your replies, I think I have it narrowed my search down to three tires and would like to get your impressions of my choices and the sizes I have picked out. I am looking at the Michelin Pilot Activ (Front 100/90 - 19, Rear 4.00 - 18), Dunlop K70 (Front 3.50 - 19, Rear 4.00 - 18), and the Shimko 712 (front 100/90 - 19, Rear 110/90 - 18). Are the metric sizes correct for my bike? It originally came with 3.50 -19 front, 400 -18 rear. Since I am the original owner of this bike, by riding style has tamed down over the years.
Thanks again for your help.

Hi bubba,
you bike left the factory with "inch" sized tires. Front; 3-1/2"-19 & rear 4"-18. These tires were "square" that is, the tire section's width = it's height.
Modern tires have Metric section measurements and ain't "square"
For instance the 100/90-19 tire specified for an XS650 front wheel has a width of 100mm and a height that's 90% of it's width
Similarly the 110/90-18 tire specified for an XS650 rear wheel has a width of 110mm and again, a height that's 90% of it's width.
So no the tire sizes ain't quite the same but yes, they are correct.
And as an added bonus, modern rubber grips the road a lot better than the original rubber did.

 

[flh_bubba]

Thanks Fredintoon,
From what I can find, the Michelins don't have a 110/90 rear tire, but they do have a 4.00". Can I mix a metric front tire (100/90 - 19) with a 4.00 - 18 "inch" rear tire? The closest I can find to 110/90 in the Michelin is 120/90, I think that may be too wide.
Thanks

 

[bikefreakjon]

Thanks Fredintoon,
From what I can find, the Michelins don't have a 110/90 rear tire, but they do have a 4.00". Can I mix a metric front tire (100/90 - 19) with a 4.00 - 18 "inch" rear tire? The closest I can find to 110/90 in the Michelin is 120/90, I think that may be too wide.
Thanks

Yes you can.

For the record, I put new k70 Dunlop tires on my 75, stock sizes.
It definitely looks vintage! And I like the gravel handling, but they are not real confidence inspiring on a hard road ride.

Also they are wearing quickly.

But they do look right.

 

[SomervilleXS650]

I'll second (or third) the Dunlop K70s. I dig the look and can't really comment on the handling, I only had a couple short rides with the older ones before replacing, but I've put 1300 miles on them now and they seem to be holding up well but time will tell there I suppose.

To Jon’s point, yes the look is right! I had to bob my front fender where it was damaged so I get to show off a little more tread than a stock ride. I think they look great.

 

[fredintoon]

Thanks Fredintoon,
From what I can find, the Michelins don't have a 110/90 rear tire, but they do have a 4.00". Can I mix a metric front tire (100/90 - 19) with a 4.00 - 18 "inch" rear tire? The closest I can find to 110/90 in the Michelin is 120/90, I think that may be too wide.
Thanks

Hi bubba,
Michelin ain't the only game in town, eh?
An XS650 Special's swingarm is identical to an XS650 Standard's swingarm and the Special's stock rear tire size is 5"-16 or 130/90-16.
A 120/90-18 is OK for width although it may need to be polled back a little to clear the swingarm's front arch.

 

[GLJ]

A 120/90-18 is OK for width although it may need to be polled back a little to clear the swingarm's front arch.

I'm running a 120/90-18 Conti/Go on my XS2. No problem clearing the swingarm, does run pretty close to the chain guard.

 

[jetmechmarty]

The width measurement on the tire isn't exact. A manufacturer may make 3 tire sizes in one mold. So, I was told by a retired tire engineer. I once measured all the 100/90-19 tires in my garage, soon after I got that info. They measured just over 90 mm to almost 110 mm. The point is, if you go big, the fitment may be dependent upon the brand.

 

[member28833]

The point is, if you go big, the fitment may be dependent upon the brand.

Very much so.
The "Dennis Kirk" motorcycle tire web site is a good source for more accurate actual size dimensions as that site does show the "inflated dimension" of most of the tires sold through Dennis Kirk.
Very informative

 

[fredintoon]

I'm running a 120/90-18 Conti/Go on my XS2. No problem clearing the swingarm, does run pretty close to the chain guard.

Hi GLJ,
your post helped me to remember the details of my own rear tire clearance problem.
Swapped to a 38T rear sprocket when I attached the sidecar.
My inner cheapskate being reluctant to buy a longer drive chain I moved the rear wheel forward instead.
Rear tire then rubbed on the swingarm's narrow frontal arch.
Buying a new two links longer drive chain fixed the tire clearance problem.
Fixed the 38T sprocket's "4-speeds+underdrive" effect by swapping to a 36T rear sprocket
& moving the rear wheel's axle almost all the way back.

 

[lorenzo]

I’m running (edited) K70’s on my XS2, because I wanted a vintage tread design, stock sizes.
View attachment 143125

On my ‘77D. I’m running Michelin Pilot Active , a modern tread design that handles really well. Stock sizes.
View attachment 143126

Did that 120/90/18 fit without rubbing?

 

[Mailman]

These were the sizes I was running on both bikes, and no they did not rub.

 

[lorenzo]

Thank you