Another example of a friendship not based solely on the forum but eye to eye shared experiences in the real world and visits to each other's homes would be Lonnie Cook. He also posts with authority here frequently.
Al--my opinion about temporary spare tires ["donuts"] is not based on theory or experience. Theories are nice, but I prefer facts. And experience is nice, but since I know the facts I've chosen to never use a donut tire, so I have no experience.
Some of the facts about donuts--
1. they are designed to be used at 60 psi cold so, if you use a donut, you need to carry a pretty powerful portable compressor on your rig along with your tire patch kit. I, personally, don't like the hard ride you get at 60 psi. I prefer to run my rear tires in the 30-40 psi range.
2. they are rated to safely handle speeds up to 50 mph (though NHTSA testing requires them to not fail at 85 mph) which is well below the safe speed limits of most modern moto tires. The ME888 Rear and the D404 I mentioned above, for instance, both have a speed limit of 130 mph, while the AM26 is rated at 149 mph. I would rather run my tires at speeds BELOW their rated speed rating rather than ABOVE.
3. a temporary spare in the size the OP needs (130/90-16) is designed to pass the NHTSA bead unseating resistance test on a rim that's 4" to 4.5" wide. The OP's rim is 2.5". So, not only is the rim too narrow, but it's a motorcycle bead profile. On a motorcycle rim, the distance between the bead flange and the bead hump (where the tire actually gets seated) is narrower than on a car rim. Because of that, every time we go darkside using a moto rim the tire will never completely get seated properly. Not a terribly big deal most of the time, as long as we are using a moto rim of the correct width (he would not be), and we don't use a ton of inflation (he would be), then we can be fairly sure the bead is not going to have a catastrophic unseating on a 50-mph right hand sweeper when we suddenly discover it has a decreasing radius! LOL! After all, it's only MY LIFE on the line. No big stakes at all.
4. the best, high quality donuts start out with a tread depth of 5/32". I don't know about you, but when the car pusher on my rig starts to get down to 5/32nds, I'm thinking it's just about time to replace it. 3/32nds is about as thin as I go.
5. donuts do not undergo UTQG testing so if I were to mount one, I'd still have no idea what kind of brake traction or lateral traction it will give me.
Now, CCjon runs donuts on his KLR rig and presumably has never had a problem. That's fine. But does that mean it's safe? Do you remember those Firestone tires from a few years back that killed all those people driving Ford Explorers? 240 deaths and 3000 injured. Massive recall almost bankrupted Firestone. Yet, it's estimated that only 1 in every 5000 of the 15-inch tires sold by Firestone to Ford ultimately failed. So, can you run a donut on your rig? Sure? And is it likely that the donut will fail? No. But if I can get better traction, longer life, higher speed ratings, and a properly seated bead from a nice fresh Metzeler or Dunlop, I'm at a loss for why I'd choose a donut instead.
By the way, I run car tires on my GS rig [rear and side] but they are mounted on wide car rims. Here's a pretty decent pic of those two tires from last summer. This was on my way back from the 2016 Rigs in the Rockies Rally.
The 40HP KLR650 is closer in similarity to his rig than the 100+ HP BMW adventure rig.
Without getting into custom wheels to run auto tires, wheels which could cost more than his whole rig, his options are a motorcycle tire or a donut auto tire. We don't know what type of riding he wants to do. What does he mean by good? Good on pavement? off road? Long lasting? Durability, Cost? what? We don't know, am guessing he is just wants to hear tire suggestions from other owners of similar rigs.
Are donut tires on the rear an option for him? Sure. So are Heidenau, Avon, Kenda or Metzler. Depends on his budget and the type of riding he wants to do.
Seems donut tires are as controversial today as going Darkside with auto tires on ANY motorcycle was ten - fifteen years ago. But we've learned a lot in the last decade. We keep pushing the envelope, learning, finding what works, what doesn't and what the limitations are. How did we find out that auto tires work great on the stock Goldwing 1500 rim but not on the Goldwing 1200 rim? Trial and error.
Why do we buy expensive custom wheels to run auto tires on adventure rigs? Because auto tires are more available world wide, auto tires cost less than MC tires and auto tires last longer than MC tires. That alone can justify the expense. But if you are not going into remote regions of the plant, why? Are they safer than MC tires? Depends on who you talk to. Anti-darksiders don't think so.
Do donut tires have limitation? Sure! I would never put one on a 100 HP BMW GS rig. The heavier more powerful faster BMW needs a stronger tire. But on a 40 - 50 HP rig, they work fine. Forget the donut instructions that were written for automobile use. You don't run 60 psi in a donut tire on a lightweight rig, The stiff sidewalls will support the rig's weight at even 20 psi, I run 38-40 psi.
We aren't running 65 - 80 interstate miles per hour either. We're cruising Ural speed, 50 - 55. We are not overheating the tires with our lighter weight and slower speeds. We're not taking tight turns or curves at highway speed so side stresses are not an issue. Again, think Ural speed.
Lack of tire depth? You are right, I wish donut tires had more tread depth but they don't and it is the only auto tire available in the US that will fit a KLR650 or the GL500. But if I can get 6000+ miles out of the lower priced donut than the 3000 miles out of a more expensive MC tires, then I'll stick with the donut. I barely got 2000 miles out the factory KLR tire.
While I ran auto tires for thousands of miles on the Goldwing rig, this is my first experience with a donut tire on the KLR. So far have no reason to think it was not a good move. Am very pleased with the performance. handling and durability. Is that opinion set in stone? Check back with me when it's time to buy a new rear tire.
Every rider is different, every rig is different. In the end you decide which tire is right for you. Then ride it. In the meanwhile, Don, you're smart to continue gathering information and opinions on what others are doing.
Ride safe and far
CCjon
NOTE: We are only talking about an auto tire on the rear, not on the front of the motorcycle.
Drone,
Now that makes a lot more sense to me. The "why" behind your statements is so much more powerful than just saying they won't work adds meat to the bones. I know that folks do all sorts of things that are not best practices but work for them anyway. The kind of background you present here builds a strong case for your statement. Thanks!
CCjon--well said, sir. I understand your decision. Did you drive that donut to Hotchkiss?
I use Avon Sidecar Triple Duty MK II 3.50-19 Tire on front GS850/Velorex and 130/80-16 on the rear. Use rear wheel from GS650.
