Metric tire size for R90?

M

MARTYH

New member

• Jul 14, 2005

• #1

I have a 1975 R90 and need a new tire. When I ask for a 4.00X18 at the local bike shops they act like I asked for dozer treads. They go to a conversion chart for a metric size. I lack confidence in these sizes. Does anyone have any experience in an alternate tire size to the stock 4.00X18.
Thanks,
Marty

 

kbasa

Well-known member

• Jul 14, 2005

• #2

I think you get a 120/18 instead.

 

D

dlearl476

Guest

• Jul 14, 2005

• #3

KBasa said:

I think you get a 120/18 instead.

Click to expand...

Actually Dave, it's a
110/90-18 Whether you can find a tire in that size or not, who knows.
FWIW, Southwest Moto tire has Michelin Mac 50/50E in the old sizes. I love them on my /5 and I think they'd be great on your S as well.
(Scroll down to the bottom of the Mac 50 page, IIRC the front and rear BMW sized tires are the last two listed).

 

F

Friedle

'99 '03 '06 National Co-Rally Chair

• Jul 14, 2005

• #4

Metric sizes

Hello Dave,

Actually it depends on the brand and model of tire.

Some 120 section 18 inch rear tires will rub against the swingarm. You might need to install a 110 section 18 inch rear instead.

Marty, why don't you go to the www.Airheads.org site and do a little research where you will soon find way more than you ever wished to know about rear tires for an airhead BMW. Lots of different "favorites" and "bests" in a couple of different sizes.

As the Airheads say, "Keep it simple". Find what works and fits for you, and then just keep using it. Trying to convince everyone else that it is the only viable choice is optional.

Friedle
Airheads Beemer Club Board of Directors
BMW MOA Board of Directors
I like OLD bikes!

 

braddog

Minnesota Nice!

• Jul 15, 2005

• #5

My experience...

I've got a '77 R100RS. I had to replace both my fronts and rears. It had Metzler ME77's, so had the 4.00X18 on the rear and 3.25X19 on the front.

They were replaced by a ME88 120X18 on the rear, and a ME880 110X19 on the front (it may be a 100X19). Both tires are a bit wider than the ME77's they replaced, but no issues at all with crowding any parts.

I chose these because I had it done at a dealer, and their prices were quite good for both the tires and the mounting. The dealer had these on hand and available, so I took 'em. I've been pleased so far. I know there are lots of other options out there, this is just my experience.

 

J

jdiaz

Blocking the slow lane

• Jul 15, 2005

• #6

SWMotoTires can get a Bridgestone BT45 in the 110 width. We have one on my wife's R90S.

 

B

bmwmick

Guest

• Jul 16, 2005

• #7

Here's another vote for the Michelin Mac50E/Mac50 in the proper sizes. 3.25X19 front and 4.00X18 rear. SW Moto always seems to have a good stock.

 

lkchris

Active member

• Jul 19, 2005

• #8

bmwmick said:

Here's another vote for the Michelin Mac50E/Mac50 in the proper sizes. 3.25X19 front and 4.00X18 rear. SW Moto always seems to have a good stock.

Click to expand...

Ditto.

BTW, there ARE NO metric equivalents to 3.25X19 and 4.00X18.

If there were, the latter would have likely disappeared.

 

M

MARTYH

New member

• Jul 19, 2005

• #9

Thanks for all the input

Well I settled on a Metzeler 120-90-18. I mounted and balanced it. It fit without any interferances. It feels good on the freeway, rides nice and smooth. I will see how it peforms when I ride it to the rally in Lima later this week.

Thanks to you all for in inputs.
Marty

 

LORAZEPAM

leave my monkey alone

• Jul 19, 2005

• #10

lkchris said:

Ditto.

BTW, there ARE NO metric equivalents to 3.25X19 and 4.00X18.

If there were, the latter would have likely disappeared.

Click to expand...

I believe that in their infinite wisdom, the germans require that you put the original equipment tire on the bike, so those sizes will be available for some time to come.

 

lkchris

Active member

• Jul 20, 2005

• #11

lorazepam said:

I believe that in their infinite wisdom, the germans require that you put the original equipment tire on the bike, so those sizes will be available for some time to come.

Click to expand...

That's correct.

The bike was tested and certified with certain tires.

Use of anything else is "outside the type certificate."

Would you fly an airliner with "parts that fit?"

 

J

James.A

Guest

• Jul 20, 2005

• #12

I wouldn't fly on an airliner, period.
I do possess the means and patience to find tires that fit.

 

1

115290

New member

• Jul 21, 2005

• #13

I'm about to change out a set of Dunlop D404's on my R90/6, and they have about 8,300 miles on them. I've always run Michelin Mac 50's before, but they've been discontinued. The Dunlops have been quite a suprise. They work well, hold the road in the rain, and have lasted far longer than I ever expected. The best part is that a set of Michelins runs almost double the Dunlop price, so the value is high. Mine are 100/90-19 F, 120/90-18 R, and I've had no clearance issues. Let us know what you choose.

 

lkchris

Active member

• Jul 23, 2005

• #14

Macadams still shown available at Michelin Web site.

Have just installed some.

 

1

115290

New member

• Jul 23, 2005

• #15

lkchris said:

Macadams still shown available at Michelin Web site.

Have just installed some.

Click to expand...

Michelin has a habit of listing items until they run low on stock. I've worked for a Michelin dealer for the last 16 years, and this business tactic has caused us no end of headaches. If I only had a dime for every time I've heard "but it's listed online", then I could probably quit working. I used the Mac 50's on my BMW for AHRMA racing, and on my Kawasaki GPZ750 for club racing, and I can't say enough good things about the way that they work and wear. Fantastic tires.