Vintage BMW Motorcycle Owners

Can the Avon am26 roadrider 100/90-18 tire be mounted on the rear of an R27 without rubbing the rear fender? If so, then I'll install the 90/90-18 on the front rim and the 100/90-18 on the rear of my 1966 R27. I have these same size Avons on my 1968 R60US, but in the roadrunner category, and they provide excellent handling and a comfortable ride. The fact that they don't look vintage is less important than their performance in rain and on drawbridge grates. Thanks, Joe

I think you might be pushing to put the 100/90 on the rear of the R27. The specs call for a 3.25x18...which ends up being nominally 82mm wide...the 100/90 is nearly 20mm wider. Not to mention the fact that the handling and turning will likely be compromised.

I used to run IRC tires on my R69S and ran into a bad set of tires. I've since gone with Metzeler Block C tires. That's my choice going forward.

What's the thoughts with doing this? Are you trying to get more use out of the barely used front tire? BTW...what's the date stamp on the tires? Hope you're not pushing the age of the rubber.

You've got Vech just up the road...does he have any input??

Kurt, I talk to Vech routinely and have discussed this topic with him. He measured an Avon 100/90 and an R27 across the rear fender at the swing arm and felt that the tire would be too wide. By the same token, in a past post by Alan Atherton, he said he had a 100/90 on the rear of his R27. The Avon 90/90 is front mount only, but Vech said it could be mounted on the rear, given the lack of hp and weight of the R27. Yet, again, I've seen the Avon 90/90-18 listed as F&R mount. The tires on my recently acquired R27 are quite old with cracked sidewalls so they have to be replaced with something, and I like Avons. Heidenau 3.25x18s are the simple solution for F&R. Still, I'd like to hear from someone who has, in fact, installed an Avon (or other brand) 100/90-18 on the rear of his R26 or R27 for a first-hand opinion. Odds are that Vech is correct.

Like the R26 and R27, 3.25 tires are recommended for my R25/3. I've been very happy with Heidenau K34s. The only time they make me at all nervous is when I have my knee down in a fast 80-85mph sweeper.

I have two R27’s and both came to me with 3.25x18 on the front and 3.5x18 on the rear. They still are wearing these tires and they do not rub. You do need to pull them out through the swing arm quite rough and taking the air out of the tire helps. I left them on and they are fine.

Are you saying your R25/3 will go 80-85 mph?

I just asked myself that too...

I'm with Kurt. I now use Metzler Block C's on all my /2 era bikes.

The only time my R27 goes 80-85 is on my trailer!
I did twice have it over 70 on the interstate. Both times resulted in generator failure so I now keep it below 65.
I have the 3.25 Heidenau K34 tires and they seem to work great.

I keep looking for a definitive Heidenaur vs Metzler Block C winner for my next R69S tires but neither ever seems to come out on top as best vintage looking tire. Guess it’s a coin toss.