Tire Size

[fjzr04]

Okay, I have reviewed many posts here and have come up with a tire selection for my 77 XS 650, Im planning on leaving it pretty much stock with the exception of suspension and ignition. I am going with AVON's AM26 Roadrunners 100/90-19 for the front and 120/90-18 for the rear, I want a bit more wider tire in the back and do not think it should affect handling bike should remain easy to lean into a turn.

Has anyone run 120's as a rear tire on a pretty much stock bike in twisty roads? Any feedback?

 

[gggGary]

IMHO don't do it unless you lace on a wider rim. IT's not easy to find a wider H spoke rim, there are some Akront 2.5" x 18" in Europe I think but it was unclear if they were drilled correctly to fit an Xs hub. Mikes has the non H 18" rims in 2.5" but they aren't drilled for an XS650 rear hub. those tire engineers spent a bit of time coming up with their recommendations.

I have these tires waiting to go on my 79 standard Bought them early this summer but a few things got in the way, now the crankshaft is twisted, but hoping to ride them next year anyways.
I had a big crotch rocket on Michelin Power pilot 3s for a bit and they were awesome! The pilot active is the best Michelin I could find to fit the XS

Michelin Pilot Activ Rear Tire
Color- --, Size- 4.00H-18
A heavy carcass tire, recommended rim width is a WM4 (2.50")

Michelin Pilot Activ Front Tire
Color- --, Size- 100/90V-19
Recommended rim width is a WM3 2.15"

I had that bike on new Shinkos as of a year ago and I was quite happy with them but those Shinkos are now on a 77 that went to live in Texas! Before the bike went south I went out and ran it pretty hard with a buddy on his 1800 wing on the hilly curvy back roads around here. They did quite well.

Bridgestone Standard Tube - 110/100-18 548723

Sold by Chaparral Motorsports
Facebook Twitter Pinterest
$17.99
Shinko 712 Series Tire - Rear - 110/90-18, Position: Rear, Speed Rating: H, Tire Type: Street, Tire Application: Touring, Tire Size: 110/90-18, Rim Si

Sold by Chaparral Motorsports
Facebook Twitter Pinterest
$48.88


I have gone to some pretty far lengths to get a wider tire on my XS. I have this rear with a matching 110 19 front but getting a brake and sprocket on it is driving me crazy (er)

http://www.bsupply.us/KTMwheels

That's a 140 on a 2.75 sun rim done by Buchanan's

 

[gggGary]

After some searching I found this rim at Buchanan's

REWM41836H EXCEL WM4 (2.50) x 18" SHOULDERED ALUMINUM RIM - 36H $248.00
Just the rim, this has the shoulders like the stock rim, add polished for $90

I think that would be a good rim for a 120 or 130 section tire.

I will guess that cost IS an object here. My best advice is that you need to adjust your thoughts a bit. The XS is a 60s 70's design street bike. The 2.15 rear rims were considered state of the art for 70's street design on Japanese and Euro bikes. If you go wide you need to bring a lot of things along for the ride. Even going to wide rims leaves you with a fairly narrow hub design with 90 degree bent spoke heads so only so much wheel stability is available. Note the dirt bike hub above has a much wider base and uses only a slight bend of the spoke head theoretically creating a more stable wheel overall.
Yes we have all gotten used to seeing wide tires, and wide LOOKS fast, GOING fast is a different animal. If you are just styling go ahead and lever on some too big tire, if you want to GO fast then pull out the money and or research gun and start planning. Think "supermoto" conversion but be aware of the issues of getting the XS tiny 33 to 36 tooth sprocket mounted on a wheel with a "too big" sprocket mount.

 

[XSLeo]

A 120/90-18 may work on the wheel but it may not fit in the swing arm.
Look at the tire you have in there, measure the space you have on both sides of the tire. Add this to the width of your tire. If the tire you want to put on matches or exceeds this measurement it wont fit.
Leo

 

[tonyc]

The best handling bikes of the era were British and they all used narrow tires. If you use a fat tire for handling it should be 16 or 17 inch low to the ground. Our bikes are not race bikes.

 

[jetmechmarty]

The 120 wide tire should fit just fine in the swingarm. The '77 has the same swingarm as a Special, correct? The Special wears a 130 wide tire.

Your bike will get through turns better with the 110 wide tire. Before you lace up a new rim, get a 16" wheel off of a Special and mount it up. The tire on that is 130/90-16. See if you like it. You may discover you prefer the narrow wheel, and you won't be out a bunch of money.

 

[fjzr04]

Thank you guys very much for the sound advice and for the information provided. Cost, as in everything, is always a factor. The reason for a wider rear tire is not for esthetic purposes, as I understand the dynamics of suspension and tires. As a matter of example, I have a Ducati 999 that came with factory 190 rear tire, I went down a size on the rear tire to a 180 for better handling on the track and road, huge improvement.

My thought process was more in line with a possible improvement one size up, grant it, suspension is currently being upgraded. It going to be an interesting adventure, I love everything about this bike and believe it may become my daily commuter once I am finished with it.

Thanks guys for all of the information, keep it coming

 

[5twins]

My bike came to me with a 120 on the rear. I used it up then went to the proper 110. It was a nice improvement and I would never run a 120 again. Lots of guys do but honestly, it doesn't work as well as a 110. Handling and ride are better with the 110, and steering is quicker.

 

[nj1639]

The 120 wide tire should fit just fine in the swingarm. The '77 has the same swingarm as a Special, correct? The Special wears a 130 wide tire.

Your bike will get through turns better with the 110 wide tire. Before you lace up a new rim, get a 16" wheel off of a Special and mount it up. The tire on that is 130/90-16. See if you like it. You may discover you prefer the narrow wheel, and you won't be out a bunch of money.

The only fly in this ointment is the drum brake torsion bar(?).......the Special has a dished bar to clear the wider tire......trying to recall if the chain guard is different too......
But, good advice.

 

[fjzr04]

Thanks Guys,

I see that Avon offers the rear tire 4.00-18 in the AM26 tire model, my question now is, what is the difference between the 110/90-18 tire size and 4.00-18? There is also a $10 dollar difference with the 4.00-18 being more expensive. So naturally, I am trying to see what the difference or advantage is.

Thanks

 

[TwoManyXS1Bs]

These may help:

http://www.xs650.com/forum/showthread.php?t=29069
http://www.xs650.com/forum/showthread.php?t=29982

 

[fjzr04]

Okay based on a brief overlook at the information I believe I can save 10 dollars and go with the 110/90-18