Vintage BMW Motorcycle Owners

I’m ordering new tires for a 1958 R60. Since I have had it, it has had a 110/90 on the rear, and a 100/90 on the front. From what I'm reading, I’m going to change that to 100/90 or 3.5 front and rear.

My question comes from the fact that I have changed the final drive from the original 33/11 to a 25/8. The lower gearing works MUCH better for me because I live at 8000’ and ride regularly to 10 and even 12,000’.

I’m not sure it really matters, but the speedometer seems to be very accurate now with the 110 on the rear. I guess my question is, is the 3.5 tire the appropriate size with the 26/8 final drive?

Thanks

The size of the tire is going to make a difference...the metric tires have a different radius. Not sure the R60 came originally with a 33/11 but the owners handbook shows it to be 25/8. The ratios are close, with the 25/8 being 3.13. 3.50x18 tires were standard for the R60 and should be close enough with the 25/8 drive.

Could be. I should have said this bike came to me originally with a 33/11. I don’t know that it came from the factory that way. At any rate, everything I can find says 3.5 front and rear, so I’ll just try them and see how it goes.

I have the original owners manual, I’ve been through it twice, and I still can’t find a recommendation on tire size. It must be there someplace.

Barrington says 3.5.

Thanks for the input

Are you sure that you mean 33/11?, which I believe was used later on /7s but not before that, the original rear ratio for the 1956-60 R60 was 32/11 (2.909:1), while the contemporary R50 and R69 used 35/11 (3.18:1), which was replaced by the 25:8 in 1961, if your R60 has the original speedo, it should be quite in error.

You may enjoy this article, https://w6rec.com/bmw-motorcycle-neutral-steering/ . A great deal of handling is related to tire size.

niall4473 wrote: ↑

Thu Feb 09, 2023 4:02 am

Are you sure that you mean 33/11?, which I believe was used later on /7s but not before that, the original rear ratio for the 1956-60 R60 was 32/11 (2.909:1), while the contemporary R50 and R69 used 35/11 (3.18:1), which was replaced by the 25:8 in 1961, if your R60 has the original speedo, it should be quite in error.

You're probably correct and I’m remembering it wrong. The original drive is packed away or I would take a look. 32/11 is likely. What's on it now and working very well for my situation is the 25/8. Is there a way to tell if a speedo matches a certain FD other than how it reads against a GPS?

weh8127 wrote: ↑

Thu Feb 09, 2023 9:02 am

You may enjoy this article, https://w6rec.com/bmw-motorcycle-neutral-steering/ . A great deal of handling is related to tire size.

Thank you. Great article. I’ve had a 4.00 on the back ever since I’ve owned the bike. I’m excited to try the new tires. It’s -17 F here this morning, so It will be several weeks, but it’s something to look forward to.

jnclem wrote: ↑

Fri Feb 10, 2023 8:15 am

Is there a way to tell if a speedo matches a certain FD other than how it reads against a GPS?

The July 2005 issue BMW VMCA News has an article listing typical final drives and speedometer matches. If you can open it up, it's here:

https://vintagebmw.org/vmca/v2n3/index. ... 1676042273

schrader7032 wrote: ↑

Fri Feb 10, 2023 10:18 am

jnclem wrote: ↑

Fri Feb 10, 2023 8:15 am

Is there a way to tell if a speedo matches a certain FD other than how it reads against a GPS?

The July 2005 issue BMW VMCA News has an article listing typical final drives and speedometer matches. If you can open it up, it's here:

https://vintagebmw.org/vmca/v2n3/index. ... 1676042273

Great. Thank you.

schrader7032 wrote: ↑

Fri Feb 10, 2023 10:18 am

jnclem wrote: ↑

Fri Feb 10, 2023 8:15 am

Is there a way to tell if a speedo matches a certain FD other than how it reads against a GPS?

The July 2005 issue BMW VMCA News has an article listing typical final drives and speedometer matches. If you can open it up, it's here:

https://vintagebmw.org/vmca/v2n3/index. ... 1676042273

Volune 32 issue #3 page 15