Topic: '78k. and the widest tire it can wear.

[Gonzowerke]

Hey all, what few posts I could find using the crap-tastic search function didn't really answer my question, so I ask;

What is the widest 17" rear tire I can run before chain rub becomes an issue. I want wider meat for more grip on my K, but I have the rim broken down for powder coating and can't take measurements for myself. I was thinking of going 160/60/17 on a 3.5 rim, after piecing together 3 or 4 posts on the subject, but am still not sure if that will work. This is with the stock swingarm and hub. I don't run a chainguard, and clearancing the brake stay is no issue.

Any thoughts? Experiences?

Thanks,

Gonzo

[eldar]

More grip how? I suppose going straight but then even with a 130 tire, that is not an issue.
A wider tire can hamper cornering performance, negating any gain from a larger tire.
A 160 should fit fine but I think you might be disappointed. A 130 fits quite fine and looks pretty good too.

[Gonzowerke]

More grip how?

When cornering.

Once I find out/decide what wider size to go with on the rear, I can then select a wider front to match. Right now, the 100/90/19 is equal to the 3.5-19, and the 120/90/17 is equal to the 4.5-17. On the rear, a 130 is 1/2 an inch wider, a 140 is 1 inch wider, a 150 is 1 and a 1/2 inches wider, so maybe the 160 is a bad choice. If I go 140/90/17 on the rear, and 120/90/19 on the front, I should be okay handling-wise. With a 130, I should be allright with the 110/90/19 I currently have on the front.

 My question now is, will the 140 clear the chain?

[Gordon]

A wider tire will decrease the size of the contact patch, not increase it, because the tire will be pinched more than a correct size tire forcing the tread into a tighter arc. 

[Gonzowerke]

A wider tire will decrease the size of the contact patch, not increase it, because the tire will be pinched more than a correct size tire forcing the tread into a tighter arc.

Oops. I didn't mention that I am going to use the proper width rim for the size I choose. Mea Culpa!

[eldar]

A 140 fits fine then, if you are using a wider rim. I have about 3/8th inch between the tire and swing arm on each side with my 130.

[KB02]

My question now is, will the 140 clear the chain?

Yes.


I am running a 160/60/17 on the stock Swingarm in my K8. A 140 will fit just fine. As far as chain guard clearance, I don't know. I'm not running a chain guard because it will not fit with the 160.

[Gonzowerke]

My question now is, will the 140 clear the chain?

Yes.


I am running a 160/60/17 on the stock Swingarm in my K8. A 140 will fit just fine. As far as chain guard clearance, I don't know. I'm not running a chain guard because it will not fit with the 160.

I don't run a guard either, it was the first thing to go when I got it. What size rim are you using on the 160? Did you go wider at the front too? What size there?
(EDIT) Nevermind, I just waded through all 19 pages of your build thread and answered my own questions!
Thanks,

Gonzo

[Retro Rocket]

A 160 will fit but you will need a 4.5 inch rear rim for the tyre to work properly, some manufacturers say that a 4.25 rim will do but it will be better on a 4.5. Clearance issues can be fixed a number of ways, the K7-8 rear sprocket carrier and gearbox output shaft are 10mm wider than earlier K models and 10 mm offset sprockets can be bought for front and back from CycleX.

[KB02]

(EDIT) Nevermind, I just waded through all 19 pages of your build thread and answered my own questions!
Thanks,

Gonzo

Yeah, and that pic reminds me of what a good idea it was to ditch that dash set-up.