Car tire on rear of sidecar rig

[elizilla]

People keep asking me what car tire DMC put on the rear of my Super10. The "darkside" thing seems like a terrible thing to do to a good handling motorcycle whose handling isn't already messed up by hanging a sidecar on it, so I hope none of you rush out and buy this tire. And I'm sure not going to add it to the tire choices list. But here's the info: it is an Economist ATR-K, size 175/55 R17.

The tire has a much lower profile than stock, so it also lowers the rear of the bike somewhat. This is perhaps an advantage for the sidecar outfit, but not so desirable with a solo. It's also a very tight fit. Here are some photos so you can see where there's less than a quarter inch between the tire and brake arm. I cannot find any sign it has rubbed, but there sure isn't any room to spare.

 

[2112]

That looks a tight squeeze, interestingly if Yamaha decide to follow the herd in tyre fashion then a 170 rear would fit a la GS12 & KTM. Just a thought...

 

[GearheadGrrrl]

Looking at the rear of my Super Ten, it looks like the only thing in the way of fitting wider tires is that brake torque arm. That, and the rim is only 4" wide, IIRC.

 

[elizilla]

I don't have any interest in wider tires for their own sake. But I suppose that if one wanted to cram a wider tire in there, it would be possible to machine a brake torque arm that has matching ends, but which curves out a bit in the middle to give more space. If you were doing one of those wheel modifications like people are always posting about on advrider/hacks, you might as well spec out a new brake arm while you're at it.

Me? I'm not diving any deeper into the rabbit hole until the novelty wears off. Give me a couple years to get the hang of what I've got now.

 

[EricV]

Just as an FYI, the brake arm is only in tension, so doesn't need to be anything too fancy. I machined one from solid aluminum, with a curve cut out for the tire to have clearance, (for my FJR, not the S10), but I'm a machinist, so it was easy for me. I know people that have just ground out more relief on the oem one, cut the whole thing in half and made various replacement bars from steel and stainless steel that have all proven the test of miles and time.

I later changed to a simple steel flat bar, 3/16" thick, 3/4" wide and just used the oem brake arm as a template to drill the holes. Radius the ends for clearance, which can be done on a bench grinder. Hit it with some black spray paint to avoid rust, or use stainless steel, if you're comfortable working with that. Use shorter bolts and bolt it up so it sits on the outside of the tabs on the swing arm and caliper. You can buy a piece of stock from ACE and other hardware stores in this size, if need be. Some stores will even cut it to length for you.

It will be more than strong enough for the task, you'll have more clearance at the tire, and just in case you get stuck somewhere on the road needing a replacement tire, you'll have more options, size wise. The 175/55R17 is not something you'll find at most tire shops. The narrowest 'common' size is 205/50R17 which is NOT recommended for a rim under 5.5" wide, but in an emergency, could be used on the hack to get you somewhere where you could get the preferred size. Just imho, this would be a good thing to do for the hack, just so you have the capability to run wider tires, if needed in a pinch.

Thanks for sharing the tire info. I have no desire to run a CT on the Super Tenere w/o a side car to go with it. Thanks for sharing all of the side car adventure with us as you go down that road. ::008::

Edit - I looked up the Economist ATR-K, size 175/55 R17 and it appears to be an Indonesian made tire that has a summer rating. Otherwise looks just fine for your use. I couldn't find any indication of expected tread life, so it will be interesting to see how long it lasts for you. They are available only on Ebay as far as I can tell, for $62.82 (Achilles ATR-K Economist), if you should require a spare. None of the normal online tire sellers have anything in that size. I normally look for all season, symmetrical tires in the 40k mile rating for moto use, but that's just my take.