Tire Size on R 80 and R 100

[grumpyone]

We have a R 80 1986 and just bought another air head a R100 Rt and both came with the wrong size tire on them. Both came with a front of 100/90 instead of the 90/90 the book calls for. The tire on R 100 RT is a ME880 and does not seem to big or rubbing any where.
Im wondering if the size needed is not made in many modern compisitions and maybe the me880 is a newer formula tire is the reason behind this change or?? And is there any problem changing the size on the front tire like that???
Thanks for the help
Jim and Esther

[rpeckham136133]

Without doing the research on that particular tire: a lot of times people will choose a certain brand/model of tire, perhaps not exactly the right fit on one tire or the other, so that they can have a matched pair concerning rubber: sane stick and cornerning in wet or dry.

I feel that, as long as the tire seats on the bead, and doesn't rub or interfere with forks, brakes, fenders etc, it should be OK.

The metric formula: 90/90 means that it is as tall as it is wide, the 100/90 means that it is a little wider. The difference between a 90/90 and 100/90 is not great. You would probably run into problems with a 120/90, f'rinstance.

[20774]

The metric formula: 90/90 means that it is as tall as it is wide, the 100/90 means that it is a little wider.

100/90 generally means that the section width of the tire is 100mm wide and the height of the tire is 90% of the width. So 90/90 doesn't mean that height and width is the same...height is 90% of 90mm. Note these are general guidelines...it's doubtful that a tire specified at 100mm wide is really going to be exactly that wide. It's even different across the various manufacturers.

Inch-size tires, while harder to find, are really the best tire for handling especially the earlier Airheads since the geometry was designed around them.

[88bmwJeff]

I'm wondering if the size needed is not made in many modern compositions and maybe the me880 is a newer formula tire is the reason behind this change or?? And is there any problem changing the size on the front tire like that??? Thanks for the help
Jim and Esther

Here's my opinion...Many people change out the front tire to a larger one because of 1) a larger tire has a bit more gripping surface (I was told this by my tire shop--could be bunk though) Overall, I doubt the size difference is big enough to have a significant noticeable difference, 2) the choices for correct size tires are dwindling, so it increases the number of options.

I have noticed, many riders have put 100/90's on the front tire instead of the 90/90. When I got my bike a few years ago, it had a 100/90 on the front, and I've replaced it with the same size tire every time. It's a little tight getting the tire past the brake calipers, but aside from that I've noticed no ill effects. Nor have any of the guru's who have ridden the bike.

I did a little bit of surfing on the net, and this is what I found. Avon, Bridgestone, and Michelin have appropriate tires with a 90/90 front tire. Dunlop has makes only a 100/90 tire. Metzeler has 90/90's via the Lasertec, which I don't like, or you can use the ME880 on the front (100/90) and the ME 88 on the rear. I'm sure there are other applications that may work. FWIW, I'm currently running the ME880/ME88 on the bike.


We have a R 80 1986 and just bought another air head a R100 Rt and both came with the wrong size tire on them.

Are we talking both bikes had incorrect front tires, or did someone put an incorrect size tire on the rear. If so, what size was put on the rear.

[Bigrider]

I have tried the larger front tire, but the original specification size 3.25x19 or its 90/90 very close equivalent gives me a better feel. The steering seems to be lighter. I'd stay with the skinny tire.

Dave H
San Antonio, Tx

[dduelin]

We have a R 80 1986 and just bought another air head a R100 Rt and both came with the wrong size tire on them. Both came with a front of 100/90 instead of the 90/90 the book calls for. The tire on R 100 RT is a ME880 and does not seem to big or rubbing any where.
Im wondering if the size needed is not made in many modern compisitions and maybe the me880 is a newer formula tire is the reason behind this change or?? And is there any problem changing the size on the front tire like that???
Thanks for the help
Jim and Esther

What year R100RT? I think monoshock R100s came with a 90/90-18. If the 100/90 fits it is a little taller and a little wider. Earlier R100's came with a 3.25 -19 front tire and a 100/90 is a similar sized tire in a metric sizing. None of these dimensions are exact and vary between tire brands and tire model. It may be a little taller and wider than a 3.25 depending on the make of each tire compared. I wager most riders wouldn't tell much difference riding in a blind test but the taller tire may make your bike lean over more on the kickstand.

[88bmwJeff]

Under the R 100 RT Faring question ; NO ROOM thead he indicated....


The bike is a 1994 R 100 RT
Jim and Esther

[tagman787]

I wanna try the blind test!