120/90/16 conumdrum

[Spad]

My XS400 has a rear rim that says 2.15", yet all the tire companies say the 120/90/16 tire should be fitted to a 2.5" wide rim at a minimum. Was the original tire mounted on the 16" XS400 specially designed for the smaller rim or what? Am I missing something here as the pickens for a rear 120/90/16 are pretty slim...Spad

 

[16VGTIDave]

Modern tires are designed for modern rims. There are some manufactures who make "vintage" or "classic" tires. Such as Duro Tires.

That said, most of us run modern tires and don't have any issues. The recommended rim size is to have the tires meet the size specified, and to have the bead seated perfectly. Installing tires on a narrower rim will have the tire "ballooned" more. Some people prefer this for esthetic reasons, even if it isn't the best for handling.

 

[Specdog]

I don't know why you have a 2.15 on the rear, it should be to be 2.50.

 

[xschris]

The 16" cast wheels are 2.50 and I think the 16" spoke are 2.15 a 120/90 16 Is what you want.

 

[Spad]

I guess I'm stuck with the 120/90/16 for now...Just interesting that Yamaha got away with putting on a tire that is not the recommended size for the stock rim:....How the bike handles is more important to me...Onward....Spad

 

[16VGTIDave]

Go back to 1981 and you will find that tires were manufactured differently. Yamaha didn't "get away with" anything. They spec'd a tire to fit the bike and wheel, when the bike was sold. It is not Yamaha's problem that you are trying to put new, modern design, tires on your 33 year old bike. You should be whining to the tire manufacturers for not still making the vintage tire designed for your antique bike...

 

[Spad]

Dave, I'm not whining, merely trying to figure out the reason and why of the problem...Your answer the manufacture and spec at the time of the bikes coming out was different then today...I was not aware that the tire people had changed the method & specs of manufacture from the time of the bikes inception to the present. Thanks for your input, and I didn't think it was an antique, just old,ha...Spad

 

[xschris]

In 1981 they used a 120/90-16 if you where thinking they used a bias tire for the bike they did not. I think the early 400's did but not the later ones.

 

[Spad]

That is interesting, went to a radial.....So the quest goes on....Spad

 

[xschris]

Here is one http://www.ebay.com/itm/KENDA-CHALL...Parts_Accessories&hash=item1c318319cf&vxp=mtr There where ones cheaper but the sellers feed back was a little weak.

 

[Spad]

Thanks xschris...It sure is looking like I'm gonna end up with the Kenda Challenger....Have time, the bike is apart and nowwhere ready to go..I still have options like changing to an 18' alloy wheel or what ever...Spad

 

[XSLeo]

I have a Honda CM400 that should have a 120/90-16 on the rear. A PO put a 130/90-16 on it. The PO bent the chain guard so it wouldn't rub on the tire. The chain does just a bit. Mostly when turning left.
As far as handling it handles fine.
You might find a 130 fits your bike fine.
A tire should have a rim width within two inches of the tire width. Well that's the rule of thumb on car tires.
A 120 is about 4 3/4 inches wide. A rim two inches less would be a 2.75.
A 130 is about 5.10. 5.19-2=3.19.
On a car tire this two inch spec works ok because car tires are designed to run with the tread flat on the ground. It stays flat on the road to corner.
A motorcycle tire does not run flat on the road. It has a round profile, so you can lean the bike over to corner.
Using a narrower rim vs a car tire helps the tire keep the rounder profile.
If you check a tire manufacturers web site you may find that they list a range of rim widths.
Leo

 

[Spad]

So far my research indicates that a 120/90/16 bias ply tire was the thought of Yamaha as a radial would require a 2.5" rim. I was hoping to have found an Avon or Continental but that doesn't seem to be in the cards without a change to an 18" wheel. All the information is well appreciated. Spad