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hudson.ny24
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VBMWMO #9228
Joined: 02/01/2017
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I need to put some new tires on my 71 R75/5. I heard good feed back on the Michelin Activ. I am ordering online, so I just want confirmation on the correct size:

Front: (3.25 H19)100/90/19 - Michelin 100/90/19 57V
Rear: (4.00 H18)110/90/18 - Michelin 110/90/18 64H

Not sure what the 57V & 64H mean. I assume the letters are the speed rating? Any idea what those numbers are? BTW, I don't want the thinner 90/90/19 tire on the front.

thanks for the help!

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Hudson
1971 BMW R75/5

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6546
I strongly suggest that you

I strongly suggest that you get inch-sized tires, the 3.25 and 4.00 designations. The metric numbers are "close" but can affect the handling of the bike as well as lower the height of the bike. DAMHIK! I have Pilot Activs in inch-sizes on my /7. In my book, 4.00x18 is NOT the same as 110/90/18.

As for the 57V and 64H, if I read info right from passenger tires, this is the load rating and the letter is the speed rating. Don't worry about these at all. The speed rating is for a constant speed of say 130/149 mph at the given load range. I seriously doubt your /5 can reach these kind of speeds!!

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

hudson.ny24
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Joined: 02/01/2017
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The Michelin Pilot Activ rear

The Michelin Pilot Activ rear tire has the 4.00x18 stated size. Their front has 3.25x19 and the 100/90/19, so I am a little confused on which to use. I know the actual measurements will vary converting from inch to metric. Most tire manufactures don't have the inch sizes, so even just as a FYI, how different is this front tire in inch vs metric?

Currently I have Dunlap tires that are 100/90/19 front & 110/90/18 rear. They fit fine and I just want to make sure I am not going narrower with a different brand/make.

Do I just go with the Michelin 3.25x19 & 4.00x18 and be done with it?

Thanks.

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Hudson
1971 BMW R75/5

schrader7032
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San Antonio, TX
Joined: 10/27/2006
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The 100 in the 100/90/19 tire

The 100 in the 100/90/19 tire means that it is 100 mm wide which about 3.9 inches. These are nominal measurements...even stating the tire is 3.25 inches wide is still nominal, but you have to start somewhere. So, having a 3.9 inch tire in front when a 3.25 inch tire is called for would not be good. Wider is not necessarily better. In fact, going through the geometry of the contact patch of the two sizes, it should take a little more effort to turn a 3.9 inch tire over a 3.25 inch tire.

The 90 in the designation means that the height is 90 percent of the width. The inch-sized tires are symmetrical. So a 90 percent reduction in height might lower the bike towards the ground. I found that out on my /7 when I was using metric tires...my bike sat up very tall so that the side stand had barely any weight on it. Switching to inch-sized tires has the bike leaning over more naturally now.

The Activs come in inch sizes. I would recommend getting the 4.00 and the 3.25 specific tires. I understand they might be a biyotch to install...I just had my local BMW shop do it, so it didn't matter much to me.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

hudson.ny24
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Thanks Kurt! That is exactly

Thanks Kurt! That is exactly the information I was looking for!

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Hudson
1971 BMW R75/5

tonyhutchinson
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Durham England
Joined: 08/17/2015
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I fitted Michelin pilot

I fitted Michelin pilot actives to my R75/7 - 3.25x 19 and 4.00 x18. Both tyres were extremely hard to fit and took forever to get the rear one to sit correctly on the rim. I had to over inflate it to get it sitting properly. They feel safe on the bike though but I doubt if I could change one at the roadside in the event of a puncture.
What pressures are you using?

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Tony

schrader7032
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San Antonio, TX
Joined: 10/27/2006
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It's been a long, long time

It's been a long, long time since I would have been able to change a tire at the side of the road. I used to change tires at my house in the old days, but no longer. With the new beads on tires, that's virtually impossible IMO. The Activs do seem to be tougher. When I need a tire changed, I pull out my credit card and cellphone!

On my /7, I run 32 front and 36 rear...I bump the rear a pound or two if I'm loaded on a trip.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

khittner
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Joined: 02/15/2012
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Go with "H" speed-rated tires

Go with "H" speed-rated tires on your airhead if you have choices available in the size you want. V-rated tires are for use at high speeds (up to 149mph), and are somewhat stickier/softer than H-rated tires. H-rated tires are rated OK up to 130mph, they'll last longer (sometimes, a lot longer) and are more than adequate for reasonable riding on public roads on an airhead.

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Konrad

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