TOPIC:

Hello.... I am building a 77 kz1000a, I have a d.i.d wm6 (3.50x18) rear rim and want the widest tire i can fit with out rubbing the chain or brake stay. It had a 130/70-18 on it...

Thanks

I was running a 150/70-18 on the same bike and rim, (stock swing arm). It was a bit farther back in the swing arm due to sprocket sizes I believe. But I used to drag race it with low air pressure and had no clearance issues. Here's a comparison site,  good luck....www.tacomaworld.com/tirecalc?tires=130-70r18-150-70r18

See below, what you go with will depend on what you use the bike for - going too wide on the tyre will potentially be ok in a straight line but may lead to interesting handling characteristics (sidewall flex) through the curves if you are a spirited rider

 

Just a quick note - a wider tyre doesn't necessarily mean more rubber contacting the ground. If you put a much wider tire on the same rim as a narrower tyre, the wider tyre will have its sides pulled in more and give a pointier profile.

The same tyre on a wider rim will result in a larger contact patch as it 'spreads out' the tire giving a flatter profile.

I'd recommend sticking pretty close to stock - wider tyres on the same rim will usually not give better grip, but will give worse handling. If you're truly after more grip, changing to a wider rim with a tyre to match is the best way to go. If you don't want to change your rim, just get the stickiest tyre you can get.

Yes wider,only straight line here

Note that all tires marked as the same size vary somewhat in physical size (width & circumference) between manufacturers.  If a 130 tire from one manufacturer clears the hard bits by a few mm, a 130 tire from a different manufacturer might rub the hard bits or, might offer more clearance.

Irish Yobo is spot-on with the description of the disadvantages of a tire too wide for a rim. Tire width & rim width go hand in hand.  Tire manufacturers will state recommended rim widths for their their tire are designed.

Good Ridin'
slmjim & Z1BEBE