Fell to the Dark Side!!!! (Car tire on the rear)

Whereas: 99.99999995% of my riding is straight up-and-down, a result of my place of residence being the flat, unfeatured topography of coastal Florida.

Whereas: 99.999999995% of my "recreational" riding is actually just getting to where I want to do recreational riding.

Whereas: Motorsickle tires is EXPENSIVE!!!!

Whereas: Motorsickle tires is SHORT-LIVED!!!!!!

Whereas: The Yamaha FJR1300 is a very powerful, but relatively heavy bike, offering very good performance and very good (for its size) maneuverability.

and Whereas: I don't want to destroy the enjoyment of the bike by going bankrupt and having to sell it, or parking it because I can't put rubber on it.





Be it resolved: I have installatificated* a car tire on the rear wheel of my FJR!!!



Yes, the bike feels different. It does work, though, and it's not dangerous, nor have any sexually-oriented attachments fallen off my body.

Handling-wise, it's "magnetically attracted" to straight ahead, takes a bit of a harder push to tip in, and once leaned the bike still steers wider than your muscle memory wants it to go. Just push a little harder on the inside bar. After 6 or 8 bends it feels normal!

I don't ride with peg-scraping aggressiveness. As a matter of fact, the only times I have scraped pegs were in low-side get-offs and the bike was sliding down the road! One in gravel, and one in an emergency stop with this much >>||<< too much front brake. Anyway, the bike does lean and turn just fine, and the tire keeps at least half its tread width on the pavement in all but the most severe lean angles. It does not climb onto the sidewall!

It wants to track with roughness in the pavement, but it's not going to suddenly shoot out from under you. It rides a little smoother, too; tar strips, reflector dots, etc. don't jar the bike as hard.

I haven't had it out in the rain, yet, because oddly enough it seems to have stopped raining once I bought the tire. I expect very good wet-weather performance with that gatorback-style tread pattern, though.

I went for a little 200-mile loop a couple of weekends ago, and this is what the rear tire looked like when I got home:


As you can see, pretty grungy in the center, not even to the wear bar (but close!) less than halfway to the edge. And this is a hard-center dual compound tire!

So I had about 10K miles on this one, got just over 11K on the previous identical tire, and they're up about $155 on the web, plus shipping, and plus mounting when they get here.

The car tire was 97 bucks, 16 bucks to ship, and I paid a guy 20 bucks to mount it. (Didn't want to try to hand-mount a car tire in the yard with C-clamps and three spoons!) On my Probe GT I would get between 20 and 25 thousand miles on a tire like this (treadwear rating 300,) and that was with an occasional autocross thrown in. At the back of the bike it's carrying about half the load it would carry at a corner of the car, so I expect to easily get 30,000 miles, looking for over 40!

So: 3 or 4 (maybe more!) times the life, at about two-thirds the unit price. I just cut my tire bill by at least a factor of 4, maybe 6!

The tire size is 205/50-17, the SMALLEST 17-inch tire made, I think. The wheel is 5.5 inches, and tires any narrower aren't available in 17 inches. Any wider and it wouldn't clear the bike's hardware. As it is I had to move one piece outward to clear the sidewall: the torque arm on the brake caliper just barely clears the tire in its stock location, but by such a small amount you need a feeler gauge to check it. That arm is responsible for keeping the brake caliper from going around the axle when you apply rear brake. I'm sure the hydraulic hose won't stretch but so many times around . . . .


I just remounted it outboard of its stock location, but had to grind it a tiny bit to clear the swingarm shape. Otherwise the tire fits perfectly. It's just enough larger diameter than the stock 180/55-17 bike tire to actually correct the speedometer! It's dead-on with my GPS now.

I didn't do any of the math to find the tire size, nor was this a possibly expensive experiment in fitment. I am #18 on the Darkside list on my FJR forum, oddly enough located at fjrforum.com, so the fitment and clearance issues were well-documented beforehand.


* in - stuh - LATE - if - i - kate - ed v. to have participated in the installatificationalization of an item, i.e. to have connected, or placed in position, for service or use.

That's awesome, a car tire on a bike!

That's interesting to say the least, is it legal?

Why wouldn't it be? It's a DOT tire (U.S. Department of Transportation) with a W speed rating (168 miles per hour) and a load rating well in excess of what it will ever see on the bike.

Car tires on the rear wheel are rather common among the really big touring bikes like the Gold Wing, and although the FJR is not that size, it's still heavy and powerful enough to be quite hard on the rear tire. It wears the same size as most liter bikes, with a bit less power and a few hundred pounds more weight than they have, especially when 2-up with luggage.

I've seen car tyres on trikes and sidecars before but never on 2-wheeler or anything that leans. I've no doubt it would be fine, or even better, in a straight line but surely the contact patch would be significantly reduced as the bike leans over and therefore reduce grip. I know from riding on squared off tyres myself that it effects the handling so I would have though a car tyre would be even worse as it doesn’t have a round profile.

Even the Triumph Rocket III rear tyre has some profile and that thing's huge!



I haven't looked into the legality of it but if it feels ok I'm sure it's fine

Even at significant lean angles it never raises more than half the tread surface off the road. It doesn't roll up onto the shoulder or the sidewall.

It might do that if you just held the bike standing next to it and tipped it over (assuming you had enough help to tip over a 650-pound machine without dropping it) but while running, there's an outward force on the leaned tire which will pull the tread down onto the road.

But like I said, I don't get to carve canyons are play in twisties here. It's all straight and flat, with intersections as my only "curves." I'm truly looking forward to a multi-year rear tire, as opposed to multi-tire years!

I guess if it doesn't roll onto the sidewall while you're riding it's ok and a hell of a lot cheaper. Bike tyres do have a lot of work to do for the contact patch area but they are expensive and don't last very long so I understand why you've done it. I used to commute 30+ miles a day on motorways and get royally hacked off having to replace tyres when I'd hardly done any proper riding (i.e. twisty country roads).

How is that going to feel when you need to quickly avoid pot holes, Manhole covers and the typical car pulling out in front of you?

I've gotten used to the feel. It came to feel "normal" pretty quickly, actually. I've done some left-right-left-right zigging in my lane when the road's empty, just so I get used to the pressure needed on the bars.

The best way I can think of to describe it is that it feels like the rake got steeper somehow, so at first the bike feels sluggish. That has gone away as my muscle memory gets updated, and the bike now feels normal, and I have no difficulty with any maneuvers I come across. Corners just as hard, you just need more pressure on the down bar. That's what feels "wrong" at first, but it's an easy adaptation.

Next time you're in the neighborhood . . . .

Yeah...next time!

I guess our brains need to get over the square look and realize how much flex there still is in the tire. I'd love to see a camera mounted to the back of the bike to see how it reacts to your motions. I am also curious to see what the wear pattern will look like in the end and how many miles you get out of it. No more chicken strip jokes for you so what will we call it...Buffalo wings?!?!

You could have just solved all of your problems by moving to Colorado. Next time you're in the neighborhood . . . .

Can't say much for his taste in music, but . . . .

In the video he says 40psi, which is way more pressure than I'm running. I run the car tire at about 30, 30.5 cold.

That's not natural, but oak express is!

That's about what I thought it would look like.

I can't believe there's that much flex in the tire, I have the same Dunlop Direzza DZ101's on my car and they feel fairly stiff.

Well, the video's not mine, and his tires are General Altimax HPs. Like it says at the beginning of the vid. . .

I picked the Dunlop out of the 72 tires available in this size on Tire Rack's site for three reasons:

First, it was under a hunnert bucks. Second, it has an aggressive tread pattern that should do well in the rain, and third, it has a slightly rounded profile. If you look at the tire, the diameter at the shoulder is a good bit less than the diameter at the center. Granted, that doesn't account for being loaded, but with pressure, one could unload the shoulders while straight, reducing wear at that point to lean-time only.

The General and the Dunlop are pretty similar so I would guess their flex would be about the same. The Dunlop is probably a bit stiffer though.

I haven't found my Direzza DZ101's to be good in the rain, but then again I have to imagine it's better then a motorcycle tire. Their hydroplane resistance sucks and I find my car get squirrelly in through puddles, but once again I don't think you are going to be puddle jumping in a bike.

Rain or shine, dude! It's how I get around.

Rode through this to get home from Pensacola: The map is 24-hour precipitation, the black line is my route.



It was a bit breezy, too. Leaning into the wind to stay in my lane, then suddenly no wind, headed for the shoulder, straighten up, then another gust, headed for the oncoming lane. If it hadn't been night-time it would've been all right, I think.

That's intense man. You are braver then I, I don't even like driving my car through weather like that.

Joey, I think anyone short of a Storm Chaser would have trouble driving through weather like that. Wfooshee, you are definitely a brave man, doing that on a high-powered bike!

wfooshee

The tire size is 205/50-17, the SMALLEST 17-inch tire made, I think. The wheel is 5.5 inches, and tires any narrower aren't available in 17 inches.

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That's huge.. The smallest 17" tire in production is the Nankang 165/35-17.

Hella flush!

They didn't designed a bike tire for nothing.. I would really hate the feeling of pushing the bike down, that's pretty dangeroes too.. But I never go in a straight line though..

If you want to drive a car tire on your bike, buy a smaller tire and stretch it a little bit. The tire stays 'flat' but you don't have to push it so hard to go around a corner. What if you ride on a different bike, first corner your on the ground pushing the bike to China..

I still don't like the look of a car tyre on a bike, I just have a bad feeling there's something that hasn't been thought of. I mean there's a reason why there's no option for a tyre like that as a motorcycle tire right? I doubt it's purely for sporty riding purposes or someone would be making such tyres for tourers specifically.

wfooshee

Can't say much for his taste in music, but . . . .

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Personally I love the song. I'd love to know who it is. As for the tire, I'm not going to gainsay you. If it works for you, great. I have enough trouble getting my XS11 to lean over. I don't need to make it even harder on me.

Dragonistic

I still don't like the look of a car tyre on a bike, I just have a bad feeling there's something that hasn't been thought of. I mean there's a reason why there's no option for a tyre like that as a motorcycle tire right? I doubt it's purely for sporty riding purposes or someone would be making such tyres for tourers specifically.

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What I've gone through in bike tires on the rear is the same thing someone would go through by putting a bike tire on a car (even more stupid!) They'd wear the center down to cords and never touch the edges. Well, that's what I've done with bike tires.

I've been told, "Get a dual compound, with a harder center." This is with a dual compund, harder center tire!

Neocrox

I would really hate the feeling of pushing the bike down, that's pretty dangeroes too.

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I'm not sure what you mean here. Pushing the bar on the side you want to go is how you initiate a turn. If you're not turing hard enough (i.e. headed for the Armco) you push a little more. I just have to push just a tad harder to get it over that first edge. I think the reason isn't so much that the tire is flat in profile, but that you actually have to lift the rear of the bike to get up on the edge of the tire. It's a small difference in physics. The round profile motorcycle tire obviously leans easier, but it's also running a smaller radius when on the sides. The car tire's radius won't change, at least not nearly as much, as it leans, and that may effect a bit of weight jacking on the rear end. And believe me, with shaft drive, I know all about weight jacking.

Neocrox

If you want to drive a car tire on your bike, buy a smaller tire and stretch it a little bit.

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Smallest (narrowest) 17" available here that fits the rim width. Narrower tire would be "spread" at the bead. That may be what you mean by stretching it, but that's VERY bad for the sidewall load.

Neocrox

What if you ride on a different bike, first corner your on the ground pushing the bike to China.

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I do get time on other bikes, including other FJRs, and it's not that hard to switch "modes," because it's not really that much different to ride. I haven't thrown one into the road yet . . . . .



I will add that on another forum somewhere, someone asked about sidewall flex. When the car tire is leaned, the low side's sidewall is stressed more than the one in the air, and he "guaranteed" that it would lead to overheating and failure. He pointed out that it would be similar in effect on the sidewall as running the tire on a car with only about 15 psi of air pressure: very low tire, with lots of sidewall stress.

I have to say that that's the only constructive and thoughtful criticism I've encountered from the naysayers. Everything else has been in the vein of, "But..... but...... You can't do that! It's ...... WRONG!!!!" with no reason given other than what they (who've never tried it, and who don't even need it) see as "obvious."

As for the sidewall flex, yes, I'm sure it's there, but it's momentary, i.e. during a turn. It's not like I'm squishing the sidewall for mile after mile after mile after mile. The bike will corner hard enough to drag peg feelers, but I don't ride like that, simply because there's nowhere around here to ride like that.

I never intended this to be a Revelation for anybody, as in "You should all try this! It's great!" Obviously a bike that's ridden hard shouldn't be dark-sided. If I lived in North Carolina or West Virginia or Colorado this probably never would have happened. I'd never consider a car tire on a liter bike or a 600. I'd put one on a cruiser if that's what I rode around here, and I might put one on a Gold Wing if I trusted it to carry the back of a 900-pound-plus bike around the turns. (That seems a bit much in the load category to me, although there are more darksiders among Gold Wings than anywhere else.)

Since my riding is flat and straight, even when out of town, it makes sense for me, on this bike, in this area.

EvilNeal

Even the Triumph Rocket III rear tyre has some profile and that thing's huge!

Click to expand...

Heh-heh. Look what I found:

You know, there are less aggressive "performance" tires with rounded shoulders...

I'm thinking of the Continental Contisport Contacts... not really the greatest performance tire, but they're good in the wet and the tread goes over the shoulder.

(interestingly, the first pic I found was exactly in your size:


see what I mean about the shoulder?

Thanks for your detailed pics, i Just went darkside. Mounted a 205/50ZR-17 BFGoodrich g-Force Super Sport A/S (W-Speed Rate). Great looking tire.
i bought the flat stablizer bar from Catfish at www.FarkleMasters.com
Leson learned, you have to go to a bike shop to mount, car tire shops do not have the equipment to mount a tire on a cycle rim.
I did have to say it was for a trailor befor they would agree to mount.
Smoth turns, great grip, fast stop!
Thanks for the help!