2016 RT With A Rear Car Tire

[gregrice56]

A couple problems solved read below.

I am running a car tire on the rear on my 2016 RT because I like to ride long distances and I don’t like to have to change my tires while out riding. I switched from a Gold Wing last year and bought a new 2016 RT. I was having to change the rear tire before 9,000 miles on the first two sets of tires. I did not like that as I sometimes do rides longer than 9,000. I had used a car tire on my Gold Wing’s for over 150,000 miles with no issues and I really liked hoe the car tire handled on the Gold Wing.

I started looking to see if anyone was running a car tire on BMW’s and came across a couple who were using them on K1600’s but no RT’s or other BMW’s. The riders using a car tire on the K1600’s only had good comments and were happy with what mileage they were getting and the performance of the tires. The only issue was that they needed a 3/8 inch spacer between the wheel and the hub to keep the car tire from rubbing the swingarm. They all said the spacer did not cause them any issues and the K1600 still tracked straight down the road.

I started researching car tires for the RT and I wanted a 195/55R17 as I knew that tire would not need a spacer because the wheel width is narrow enough. Of course no one makes a 195/55R17 tire so I kept looking. I finally found a 195/45R-17 YOKOHAMA S.DRIVE XL that would fit and not need the spacer. I rode about 5,000 miles on this tire and it felt good except it caused the odometer to record more miles than I was riding since the diameter was smaller than the OEM tire. It also reduced my MPG’s slightly. It felt good but I did not like the tradeoffs so I kept looking.

I use a website that allows me to compare tires to get the diameter and other measurements, https://www.tacomaworld.com/tirecalc?tires=180-55r17-205-50r17

During this time I contacted the person who made the spacer for the K1600 riders and had him make me a spacer just in case.

I finally found a nice tire that had great test and driver reviews and I ordered it. It is a 205/50ZR-17 BF Goodrich g-Force COMP-2 A/S XL - UTQG: 400 AA A. I took the wheel to the local tire place and had them mount it. I mounted the tire to the RT to see if I would need the spacer and found I did need the spacer as the tire would touch the swing arm. So I put the spacer between the wheel and the rear hub and I used GSA wheel bolts as they are a little longer and would work with the spacer. The person who sold me the spacer told me this trick.

I put 37 PSI in the tire and went for some rides and I found that 37 PSI was too much pressure and I reduced it to 34 PSI and that is where it felt great. I road around 8,000 miles with the tire doing some 1500+ mile days and it really felt great and did not cause me any problems in the twisties. I was even able to drag a few things with the car tire.

I now on my second BF Goodrich g-Force COMP-2 A/S XL and have over 16,000 miles and still love the tire and the setup.

There still was one problem. The BMW TPMS would flash yellow with around 33 PSI and more all the time and it would turn red and be real annoying if the pressure dropped below 33 PSI like when it was cold out and or raining. On my Gold Wing I had the same issue so I reversed the programming of the TMPS sensors making the onboard system think the rear was the front and the front was the rear. This solved the issue of the TPMS light coming on with the Gold Wing.

I have the GS-911 and saw it had some TPMS learning capabilities and started asking questions could I also reverse the TPMS sensors and fool the BMW RT into thinking the rear was the front and the front the rear. Well everyone said NO!

I thought that was not correct so I started playing around and I read all of the user manuals to see how to program the TMPS with the GS-911 and I started testing. One thing I found out was that you need a TMPS tool to wake up the sensors which I had as I had to do that with the Gold Wing. You also need to know the TPMS sensor ID number which is printed on the sensor in the tire and is stored in the RT’s onboard computer. The GS-911 will also display the TPMS sensor ID.

I got everything setup and the GS-911 connected to the RT and I started the TPMS sensor functionality in the GS-911 and I saw the TMPS sensor ID for the front and rear in the GS-911 software. I took a couple photos of these numbers so I would not forget them as I needed them to reprogram the computer. I used the TMPS sensor wake up tool and then ran the GS-911 software and the sensors did wake up and I could read the tire pressure and the tire temperature.

I tried to use the manual TPMS programming functionality in the GS-911 software and program in the rear sensor ID for the front and the front for the rear but it would not take. I tried a few times thinking maybe I made a mistake. I then thought maybe I need to change the sensor ID’s to something that is not already stored into the computer so I programmed the front to 1111111 and the rear to 2222222. I then tried again to program the front with the rear TPMS sensor ID and the rear with the front TMPS sensor ID and it worked!

Now on my dash the TPMS does not light up yellow or red when I only have 32 to 34 PSI in the rear tire. I only need to remember that I have the sensors switched. The front reads 34 PSI and the rear reads 41 PSI.

I should get around 20,000 miles out of the rear tire.

[Pete1200]

I'm really not sure what to make of this. Either it's a wind up or the bike must handle weirdly with the wheels being out of line. Or, of course, BMW and the tyre manufacturers really missed a trick here!

[B787MECH]

Unbelievable! This is wrong from every angle, what do you do when you get to a bend? I can see it on a sidecar combination but on a solo!? And to think we worry about squaring off our bike tyres, you start with them squared off! Sorry to be negative but in the UK you'd be laughed off the road, not to mention invalidating your insurance etc. Still, as they say, only in America!


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[Paggers]

I think it's a positive and creative solution - but one that wouldn't work here in the UK. I think it's important the remember that the USA is a country of wide open roads and very little in the way of what we would call 'twisty' roads. You can easily travel hundreds of miles in a straight line there. Here in the UK (and in Europe in general) even our major roads constantly change direction, ranging from gentle bends to fairly severe ones. We also have to deal with road surfaces that are rougher than many of the major roads in the USA.

It wouldn't work here - in fact I'm fairly sure it would be illegal in this country; it would certainly count as a modification and I don't think the bike would pass the UK government annual safety test (MoT test),which would in itself make the modification illegal. But I can see the appeal of not having to change tyres as regularly. Having just replaced the tyres on my RT - at a cost of £300 - I'm definitely not looking forward to having to replace them every ~6k miles (that's 6 months riding for me).

So if it works for you, more power to you. Each to their own.

[LAF]

Well I think you need to take a look at this before you comment on what roads are what in the US and UK.



http://www.ifitweremyhome.com/compare/US/GB

You are like 2.5 of our 49 continental states.  You do not have to travel anywhere in a strait line in the USA.

No disrespect but not a fair example of our roads compared to yours.

[Paggers]

My point was more that there is potentially some rationale to the above in the USA where it is possible to drive for many hundreds of miles without meeting what we would call a bend. By comparison the UK just doesn't have roads like that. I'm sure the USA has some twisty roads, but as a country of some 9 million square miles you also have an awful lot of nice straight interstates. We live in a country that you chaps could probably drop into a quiet corner of the States without noticing, and our road designers simply don't believe in straight lines.

[timminator]

My point was more that there is potentially some rationale to the above in the USA where it is possible to drive for many hundreds of miles without meeting what we would call a bend. By comparison the UK just doesn't have roads like that. I'm sure the USA has some twisty roads, but as a country of some 9 million square miles you also have an awful lot of nice straight interstates. We live in a country that you chaps could probably drop into a quiet corner of the States without noticing, and our road designers simply don't believe in straight lines.

You are both right, it depends greatly on what part of the US you live in.  The shortest distance between 2 points is always a straight line, and highway engineers always shoot for that, whether in the UK or the US.  It's the obstacles that nature puts in the way that cause roads to bend.  If you live in the Midwest, which I have, roads are VERY straight, you can go a hundreds of miles across Nebraska, Kansas, etc...without hitting a curve.  I'm in the Pacific Northwest now, and all we have are mountains and rivers, there's not a straight road anywhere.


Now, back to the tire, I'm guessing in a turn the tire stays flat and the sidewall flexes to adjust to the lean angle of the bike.  If it was rolling onto the sidewall, that tire would not hold up at all.  Would love to mount a camera back there and watch the tire react in a sharp turn.

[gogs01]

It would appear that the OP is not the only person to have fitted a car tyre to the rear of a motorcycle and done many thousands of  happy, safe miles on them.
While I'm naturally sceptical, it does seem that there's a fair bit of evidence to support the idea that a car tyre can be successfully used on the rear of a motorcycle - and last three or four times as long. That makes me wonder why tyre manufacturers can't make it work - even some kind of hybrI'd which would last twice as long (and cost less, not more !) could be a major step forward for high mileage riders  -  couldn't it ?? 

[guest2360]

I think it's not just the profile that's a problem.  In the Can Am world their Spyders are fitted with what look like car tyres but are marked for motorcycle use only.  The reason being they are more lightly built due to a lot less weight.  This reduces their life considerably over a standard car tyre which had the same profile.  But due to the heavier construction they need to run a quite low pressure i.e. 18 to 20 psi.  On an RT weighing 100 kgs less than a Spyder an even lower pressure would be required for it to give anything but a solid feeling ride and presumably any grip.

[Casbar]

Read another report on car tyres on an RT, some guy has done some research. Apparently, when new, the tyre behaves like a squared off bike tyre, but as its used it starts to develop the profile of a new bike tyre, so improves with mileage. He also managed to measure contact patch, and again when leant over the contact patch of the car tyre was less, but still more than a bike tyre. The only issue seems to be they don't turn in quite so well and need a bit of effort to maintain a line through a sweeper.


Lots of guys using them in the States, so might not be as bad an idea as we all think. Of course in the UK, that would be illegal as far as I know  8)

[B787MECH]

Read another report on car tyres on an RT, some guy has done some research. Apparently, when new, the tyre behaves like a squared off bike tyre, but as its used it starts to develop the profile of a new bike tyre, so improves with mileage. He also managed to measure contact patch, and again when leant over the contact patch of the car tyre was less, but still more than a bike tyre. The only issue seems to be they don't turn in quite so well and need a bit of effort to maintain a line through a sweeper.


Lots of guys using them in the States, so might not be as bad an idea as we all think. Of course in the UK, that would be illegal as far as I know  8)

I still can't think of a quicker way to ruin your bike. In exchange for extra mileage from the rear tyre you would completely ruin the handling with mismatched profiles front and back and a tyre compound not designed for motorcycles, making it dangerous imo. This makes me conclude that anyone doing this to their bike is not riding it at any sort of speed or lean angle, with very different priorities to most of us. If they're getting 20,000 miles from the rear tyre, what do they expect to get from the front? In 'normal' circumstances you might get about 8/10,000 miles max.If they're changing it at 8000 miles then it negates having a rear that lasts 20,000.


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[Casbar]

I still can't think of a quicker way to ruin your bike. In exchange for extra mileage from the rear tyre you would completely ruin the handling with mismatched profiles front and back and a tyre compound not designed for motorcycles, making it dangerous imo. This makes me conclude that anyone doing this to their bike is not riding it at any sort of speed or lean angle, with very different priorities to most of us. If they're getting 20,000 miles from the rear tyre, what do they expect to get from the front? In 'normal' circumstances you might get about 8/10,000 miles max.If they're changing it at 8000 miles then it negates having a rear that lasts 20,000.


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You know I would have agreed with you, but having read a few threads on US RT forums, there seems to be many experienced and technically aware people who put up a very convincing argument backed up by actual knowledge and data, not just supposition. They have been doing this on Pans for years. Not for me, but there must be something in it, as some of the guys also ride roads with bends as well. 

[T6pilot]

I'am one who believes if you have a accident with a non motorcycle tire on your bike, you could be sited by law enforcement and if a insurance investigator discovers this your claim my be denied

[Paggers]

Can I observe (hopefully without getting shot down in flames) that we seem to have moved away from the merits (or otherwise) of the approach and into firmly held personal opinions about safety and legality. I think we are all old enough to make our own judgements in those areas. Certainly for me it's an interesting idea but one I will not be trying myself. If other people want to try it, that's entirely their choice. There are people out there who ride strange contraptions with 3 wheels, and - even worse - Sports Bikes! Which just goes to prove that the community of bikers is made up of all types. Live and let live say I.

[guest2360]

Can I observe (hopefully without getting shot down in flames) that we seem to have moved away from the merits (or otherwise) of the approach and into firmly held personal opinions about safety and legality. I think we are all old enough to make our own judgements in those areas. Certainly for me it's an interesting idea but one I will not be trying myself. If other people want to try it, that's entirely their choice. There are people out there who ride strange contraptions with 3 wheels, and - even worse - Sports Bikes! Which just goes to prove that the community of bikers is made up of all types. Live and let live say I.

I'm not offended by my Spyder being described as a contraption , just glad I haven't got a sports bike as well.