2 front tires?

[paulfinney2]

When order tires by phone for my '76 R75/6, the dealer said he could fit me with Metzler Lasertec 3.25x19 up front, and Metzler Marthon ME880 110/90-18 on back. That was a couple of mos ago, and I haven't been riding that bike in winter, as it has no fairing, but today when I when to fool with it, I saw that the rear tire, the ME880, had "FRONT" printed on the side of the tire. So did the Lasertec, so now I have two front tires.
I called the dealer, and he said he would see what he could do, but the tire has 15 miles on it, and he said he can't send it back. He also said he was having a hard time finding tires to fit that age bike[?!].
What kind of problems might I run into by leaving the ME880 FRONT tire on the rear?

[PacWestGS]

Probably none, Paul

That tire size may be all that is available in the size you need.

As far as running that 'Front' tire in the back, you will have a lower lean rate (something you might like). It will probably have less carrying capacity but not by much. And will have a better rain grove that will wear out faster than a regular ME880 rear tire, but still last a long time.

Hope things work out but 'I can't think of any thing bad from that'.

[Stuff2C]

Size matters :D

I mounted a rear tire backwards one time and didn't notice it until it was almost done :jawdrop When someone at a rallye pointed it out. I finished it B4 I chanced it.

[pmdave]

The primary difference between a "front" and a "rear" is the tread pattern. There are also directional arrows on tires so you can orient them in the proper direction to help prevent belt separation. When a "rear" is used on the front, or a "front" is used on the rear, the tires should be reversed, so the arrow points backwards.

Yes, today's motorcycle tires are getting wider and fatter, and there are fewer tires made in the good old 400 x 18 and 3.25 x 19 sizes suitable for the airheads. However, if anyone says they can't get those sizes anymore, they are really saying, "I don't want to order one or two tires from some supplier other than the one I'm using, and besides, I'd like to encourage you to flog that old dinosoar and buy a new $15k bike that you can't work on yourself."

It's true that mounting tires on say, a 1200GS is an arm wrestle, better done with a shop tire mounting machine. But it's also true that 400 x 18 and 3.25 x 19 tires aren't difficult to mount with simple tire irons and a bit of knowledge.

I am currently running Pirelli Strada MT 68 (rear) 4.00H-18 and Strada MT 69 (front) 3.25H-19 on my 1971 R75. I also have a local "dirt bike" shop that can provide just about any tire I need (at a good price) and will mount and balance tires, even if I have to buy it somewhere else. Look around. If only "tubeless" tires are available, I use an innertube on the airhead spoked wheels. I have a new set of "tubeless" Avons that say on the sidewall "if used on tube-type rims, use an innertube".

There are lots of old airheads still being maintained, and IMHO any BMW dealer worth visiting will have correct tires for your old boxer. It may be true that Metzeler no longer offers a 4.00 x 18 REAR, but there are many other brands. So, if your dealer gives you flak, just order tires from one of the mail order sources, and mount them yourself. Try www.motoxoutlet.com, www.mawonline.com, www.competitionAccessories.com, www.denniskirk.com, or www.chaparralmotorsports.com.

In a recent Cycle World, Chaparral lists Bridgestone Spifire 100/90H19 FRNT at $54.97 and 120/90H18 RR at $58.97. For exact replacement sizes, consider the Michelin M50E 3.25-H19 FRNT $62.97; M50 4.00H-18 REAR $77.97

BTW, always ALWAYS use a new innertube with a new tire. Get a good tube, say a Michelin.

pmdave

[Stuff2C]

The primary difference between a "front" and a "rear" is the tread pattern. There are also directional arrows on tires so you can orient them in the proper direction to help prevent belt separation. When a "rear" is used on the front, or a "front" is used on the rear, the tires should be reversed, so the arrow points backwards.

pmdave


What? :huh

If the tire is moved from front to rear the rotation is the same, Right? :confused:

[paulfinney2]

Thanks. So you don't see any mechanical or safety issues of running front tires on the rear [other than trying to explain which way I really am going]?
What kind of mileage or wear can I expect from the Spitfire or from the
M50s?

[20774]

What? :huh

If the tire is moved from front to rear the rotation is the same, Right? :confused:

It's my understanding that the front see's some decent forces on it when you use the front brake whereas the rear tire gets most of its forces from acceleration. These two forces are in opposite directions, hence the need to be concerned with the arrows.

Kurt in S.A.

[mullerjd1]

Avon still has a rear in the size you need.

[pmdave]

The installation arrows on a tire are for it's intended use. A rear tire provides driving force in the forward direction. A front tire provides steering and braking forces--which are in the rearward direction. IOW, the rear tire pushes forward, the front tire pushes rearward. The tire carcass is built accordingly.

pmdave

[Stuff2C]

Thanks for clearing that up for us arrow challanged in the crowd (me).

[lkchris]

It may be true that Metzeler no longer offers a 4.00 x 18 ...

Better said, Metzeler's USA importers don't, as plenty are available in Germany as it's illegal to put any other size on the rear of an Airhead.

I say if Metzeler's importers won't support Airheads, don't support them.

[R100RS]

Yes, today's motorcycle tires are getting wider and fatter, and there are fewer tires made in the good old 400 x 18 and 3.25 x 19 sizes suitable for the airheads. However, if anyone says they can't get those sizes anymore, they are really saying, "I don't want to order one or two tires from some supplier other than the one I'm using, and besides, I'd like to encourage you to flog that old dinosoar and buy a new $15k bike that you can't work on yourself."Or, they're saying: "I don't know how to use the cross-reference table that appears in every one of my parts supplier books."

A 100/90-19 Front and 110/90-18 Rear will be just dandy. Just make sure to use tubes in wheels that require them.

[pmdave]

A 120 rear tire provides a slightly beefier tread, but a 120 can be a snug fit between the swing arm and brake shoes, and may rub on the swingarm on the RH side. (we're talking double sided swing arms here)

One trick is to use a slightly wider RH seal ring to offset the rear wheel another mm or 2 to the left. That provides clearance from the driveshaft housing on the swingarm.

The other trick is to insert a piece of plastic sheeting ("Visqueen" to you nail pounders) between the tire and swingarm and between tire and brake shoes on the final drive. That allows you to ease the tire through the snug opening.

Since we're on the subject, whenever fiddling around with the rear wheel, secure a tie-down strap between the centerstand and front wheel (or between centerstand and the header crossover pipe) to prevent the stand from retracting while you're shoving and pulling on the wheel to get the tire past the obstructions. It's awfully embarrassing to have the stand retract with the rear wheel loose.

pmdave

[James.A]

I deflate a mounted rear tire to make it soft for squeezing into place and then re-fill after it is in position.

[20774]

A 120 rear tire provides a slightly beefier tread, but a 120 can be a snug fit between the swing arm and brake shoes, and may rub on the swingarm on the RH side. (we're talking double sided swing arms here)

One trick is to use a slightly wider RH seal ring to offset the rear wheel another mm or 2 to the left. That provides clearance from the driveshaft housing on the swingarm.

pmdave

According to the ETK, there are two sleeves for this purpose. One is 10.7mm wide (36 31 2 301 737) and the other is 9.2mm wide (36 31 4 038 142). If the bearing stack is set up right, it should be pretty easy to swap out this spacer sleeve to move the tire over.

Kurt in S.A.

[lkchris]

Or, they're saying: "I don't know how to use the cross-reference table that appears in every one of my parts supplier books."


This is mythology.

There are NO metric equivalents to 3.25X19 and 4.00X18.

That's why they're still made.

Close enough is always good for GM and Ford but shouldn't be for BMW.

[paulfinney2]

The nice dealer called me back and said he found a tire to fit.
Metzler Perfect ME77 4.00-18.64H. Exchanged and mounted for free, and he spotted me the $5 difference in price.

I was going to just ride the ME880 FRONT, but was converted by the discourse on accelerating and braking forces in carcass design. Thanks pmdave.