The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Julio A. on April 15, 2011, 05:10:03 AM

Title: Tire sizes!!!!
Post by: Julio A. on April 15, 2011, 05:10:03 AM
My Tires are called for replacement already.

The User manual called for a 3.25 S 18 for the front and a 4.00 S 18 for the rear.

As the selection of tires for this bike here is pretty limited, I was only able to find a pair of metzeler lasertec tires. But it is in a different measurement.

The measurement was 90/90 - 18 front and 120/90 - 18 rear.

I'm a little worried in buying a possibly different size since the tire I'm using right now is in the correct measurement yet it barely clears both the swing arm.
Title: Re: Tire sizes!!!!
Post by: bruce_launceston on April 15, 2011, 05:55:13 AM
Hi Julio, I run 100/90 on the front and a 110/90 on the rear. Most 120/90 rears are too tight although some will squeeze in. See if you can swap it for a 110.

Technically a 4.00 (inch) would be a 102/90 (mm) and a 3.25 would be a 81/90.

I find the Bridgestone BT45's excellent if you can find them.
Title: Re: Tire sizes!!!!
Post by: Julio A. on April 15, 2011, 08:00:43 AM
Wow, thanks! I found the info really helpful. I'll give the Bridgestones a try. Hopefully I'll find a pair. They're a little cheaper than Metzelers too!
Title: Re: Tire sizes!!!!
Post by: Bob_Roller on April 15, 2011, 08:09:27 AM
The 120 rear tires can be a bit of a hassle to get the wheel/tire on and off the bike .

You need to deflate the tire before attempting to remove the wheel .

Title: Re: Tire sizes!!!!
Post by: Julio A. on April 15, 2011, 11:52:46 AM
Just out of curiosity, between the 90/90 and the 100/90 front tires that both fit the R65, is there any significant difference in regard to feel, cornering and other stuff?
Title: Re: Tire sizes!!!!
Post by: tvrla on April 15, 2011, 12:09:25 PM
The 90/90 looks real small while the 100/90 looks right, and comparable to the 3.25. It should handle just fine though. The larger bikes take the 100/90 x 19 - some friends have accidentally used the 90/90 and they rode just fine.
Title: Re: Tire sizes!!!!
Post by: montmil on April 15, 2011, 05:32:03 PM
I like the way my '81 R65 turns in on the corners. It's a 100/90 Bridgestone Spitfire. 110/90 Spitfire on the rear. The Spitfires are a wee bit more economical than the BT45s. Both excellent tire values. Plus, the bike looks pretty racy with these sizes mounted.

Monte
Title: Re: Tire sizes!!!!
Post by: Bob_Roller on April 15, 2011, 06:00:23 PM
An option that you do have, if you can't find a rear tire narrower than a 120 width, is to replace the top hat/ compression spacers that stick out of the wheel bearing seals .

You can get one that is just a bit under 4 mm .

Install it on the side of the wheel that goes up against the final drive .

You will also need a thinner washer under the axle nut .

Make sure that you have at least one thread protruding through the nut when you get done tightening it up .
Title: Re: Tire sizes!!!!
Post by: Julio A. on April 16, 2011, 02:19:50 AM
Unfortunately, There is no Bridgestone BT45's or Spitfires available here. The Metzeler Lasertecs weren't also available in the correct size.

I'm settling for a pair of Pirelli City demons as these are the only ones available in the correct bias sizes.

I appreciate all the input guys, many thanks!  :)

Title: Re: Tire sizes!!!!
Post by: Rob Valdez 79 R65 on April 16, 2011, 03:23:43 AM
100/90 front and 110/90 rear for me.  I am very happy with the way the bike handles.

(Bridgestone Spitfires, but that is irrelevant for you, Julio.)
Title: Re: Tire sizes!!!!
Post by: Barry on April 16, 2011, 01:06:57 PM
Quote
I'm settling for a pair of Pirelli City demons as these are the only ones available in the correct bias sizes.  

Pirelli City Demons tires are available in 4.00 x 18 I fitted one a couple of years back.  It was easy to fit on the rim (compared to a Metzeler) and slides in past the brakes shoes fairly easy. Wears well too. Hard to give a definitive view of the handling as any new tire is a revelation after an old worn squared off one.
Title: Re: Tire sizes!!!!
Post by: raypond on April 17, 2011, 02:24:53 AM
I reckon stick to the original tyre sizes, especially on the front. The PO of my bike had put 100/90s on the front and so for a while I just replaced them with the same. I then put on the specified 90/90 and it transformed the handling - lighter, quicker, goes around corners better. I did use BT45s but seem not be able to get them here in Oz anymore. I currently have Michelin Road Activ  tyres front and rear and I'm very happy with them. Too early yet to know how they wear.
Title: Re: Tire sizes!!!!
Post by: Justin B. on April 17, 2011, 08:36:28 PM
I am running 90/90-18 on the front and it gives nimble steering where the 100/90 will have some "understeer".  The newer monoshock Airheads specified 90/90-18 front and 90/120-18 rear.  I have that combination on the Junkyard Dawg and it handles great.
Title: Re: Tire sizes!!!!
Post by: rwait on April 24, 2011, 09:04:16 PM
Also consider the relatively new (been out maybe a year or so) Continental Go's.  I'm on my second set and have really been happy with them.  They come in sizes to fit the R65.  Check out this link - http://www.tiresunlimited.com/ALL%20TIRES/Continental/continental_conti_GO.htm.  I ordered both sets through this company in Ohio and have been very happy with the price and service I received.

RW