Here is a tire size to rim fitment chart.

If you go outside of the fitment shown on this chart, you will be deforming the tire to a shape it is not supposed to have.

When you jam a wide tire on a narrow rim, the tread cross section becomes very round and the contact patch to the road is reduced.  Poor traction and accelerated wear is the result.

Dave wrote on 06/05/25 at 11:32:25:


Dave, can you explain this “the tread cross section becomes very round and the contact patch to the road is reduced”.

Would a lower aspect ratio adjust for some of the rounding?

Would a 180/55 have its contact patch reduced to something like a 160/60?

The chart seems to suggest a wider rim than is truly necessary as “STD”.

My Kawasaki Vulcan S 650 comes standard with a 160/60–17 on a 4.5” rim.  It’s in the acceptable range per the chart, but the chart suggest 5.0” would be the ideal standard.  Seems really big.  And for a 180/55, it’s kinda off the chart.  Implying it needs like a 6” rim or something.  Lots of guys are running the 180/55 on the stock 4.5” rim and rave about it.  Not my thing - I like the stock 160/60.

The chart seems biased towards rims wider than are truly necessary or optimal.

Back Rim is 15x2.75

Interesting Easy Rider.  The dude in that other video sure had some issues with the 150/90.  Flatter fasteners on the inside of the fenders should eliminate any rubbing concerns.

Thanks Axman.  The info about the taller aspect ratio makes sense.  I'm still hung up on the chart suggesting you need like a 5.5+ inch rim for a 180-190 tire.  

Maybe reaching for info, but does a tubeless vs tube tire factor into this tire width/rim size fitment in any way?