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The Dark Side – The Love of Car Tires on Motorcycles

Darkside Motorcycle Car Tire

Dark Siders


A “Darksider” is the term used to describe a rider that uses Darkside Motorcycle Tires. Darksiders simply replace their rear tire with a Car Tire.

Running car tires on motorcycles is commonly known as “The Dark Side”. Those riders on car tires are known as “Dark Siders”, and they generally only fit a car tire to the rear wheel of the motorcycle.

Regular Riders


Riders that run motorcycle tires on both front and rear wheels are known as “Regular Riders”.

The Exceptions


There is always an exception, and I am guilty of being one of those riders. As my daughter is in a wheel chair, I built her a wheelchair accessible sidecar. I exchanged my FJ1200A rear motorcycle tire, with a flat profile motorcycle tire. Yes, it is not a car tire, but it is flat profile. The tire is designed to fit on antique motorcycles that generally have wooden spokes and square profile tires. I selected this tire as the Yamaha will no longer lean and the sidecar has a car tire fitted.

Ignoring these exceptions such as sidecars and trikes, the purpose of this article is to discuss fitting a car tire on the rear of a two wheel motorcycle.

The Love of Car Tires on Motorcycles


A discussion about the fitting of a car tire on a motorcycle rim will produce a different response according to which motorcycle rider you talk to. Like almost everything in this world, there will always be two sides, and each side will have reasons why they support the point of view that they hold. There may also be people that have never considered the topic and hold no opinion at all.

A good example is Lane Splitting. You will always find riders that say it is safer to lane split, while other riders debate against it.

“If you don’t lane split, you can be rear ended”.

Or

“If you do lane split, you could be hit by a car changing lanes”.

“What is your preference Sir, Regular or Dark Side?”

Motorcycle Darkside Rear Tyres

Spelling


You will find this subject is mentioned on the Internet using the following three methods of spelling:

The Dark Side – The Darkside – The Dark-Side

I prefer to use the following: The Darkside.

As I am an Australian, I will occasionally make a mistake and use Tyre (Australian) instead of Tire (USA), as I am trying to use American English to suit the majority of readers and it is hard to teach an old dog new tricks.

Happy Tyre

“But who cares anyway, a tire is a tyre”.

Before investigating both sides of the fence and reasons why riders are passionate about the grass on their side, lets first examine the basics.

Tire Rim Fitting


Fitting Motorcycle Tire

The first question to address is, will a car tire fit correctly onto a motorcycle rim? Well we do know one fact that is not subject to opinion. A motorcycle tire is designed and tested by manufactures to fit on a motorcycle rim; likewise a car tire is designed and tested by manufacturers to fit on a car rim.

That does not prove that one will not fit onto the other, it only proves that it was not designed to. “A bucket is designed to carry water, however, I can carry water in a fry pan if I wish”.

In the following photos you will see that the rubber where the tire meets the bead is the same size and shape, whichever combination.

Motorcycle and Car Tire (Tyre) Comparison


Comparing the Bead, Shape and Size

Motorcycle Car Tyre

Motorcycle Car Tire

Motorcycle Tire on 16″ Car Rim

Motorbike Tyre on Car Rim

NRF Car Tire on Goldwing Rim

Car Tyre on Motorcycle Rim

Motorcycle Tire on Motorcycle Rim

Motorcycle Tyre on Motorcycle Rim

Car Tire on Motorcycle Rim

Car Tyre on Motorcycle Rim

Image Source: Click Here

To view measurements and technical details: Click Here

As you can see, the Bead Flange, Bead Seat and Bead Hump are the same size and shape, and regardless of which tire is on which rim, they fit well either way. Knowing this, what else would need to be considered before installing a car tire onto a motorcycle rim?

Tire Shape


Motorcycle Rear TyreMotorcycle Car Tyre

Is the V-Shape of a motorcycle tire designed to allow a bike to lean smoothly from side to side? Does the squarish corner of a car tire create less traction (contact patch) on the road while leaning or turning on bends?

Motorcycle manufacturers will inform you that the shape of a motorcycle tire is designed to provide maximum traction while leaning and that a motorcycle tire is made of different compounds throughout the tire. A harder compound in the center for wear durability and a softer compound on the edges for grip on leans. Whereas, a car tire is made with the same compounds throughout.

Dark Siders will prove that there is the same contact patch or even more on a car tire and some claim they cannot feel any noticeable difference in smoothness from left lean to right lean. There are Dark Siders that do notice a difference, but will state that the difference is minor and easy to get accustomed to.

Therefore, it would come down to handling and safety, which we will investigate shortly.

Liability


Liability Law

The obvious next question would be liability in an accident. As motorcycle manufacturers strictly warn purchasers in the manual to not install automobile tires on a motorcycle, warning it could cause serious harm or death, fitting a car tire to a motorcycle would expose the rider to liability risks if an accident did occur.

Cost


Motorcycle Disability Funding

This is a question that does not need thorough investigation as a car tire will cost about $70 USD and a motorcycle tire will cost more than $150 USD.

Wear


Worn Motorcycle Tire

Motorcycle rear tires last between 2,000 miles (3,200 km) to 4,000 miles (6,400 km), whereas a car tire fitted to a motorcycle rear will last over 20,000 miles (32,100 km).

So what we really need to do is ask the experts. We will compare the pros and cons of each side of the debate from the perspective of the rider. Everyone has a right to their opinion and I thank and respect each rider for sharing their knowledge with others.

Pros and Cons of the Rider


Let us take a look at the pros and cons of the following three categories, from each side, to better understand the riders point of view.

1.Handling & Safety

2. Wear & Cost

3. Fitting

Darkside Rider (Motard Squid)


Pros of a Car Tire:

Motorcycle Out of Control

Handling & Safety: “People would be surprised on how well these tires ride.”

Tyre Wear IndicatorWear & Cost: “A car tire provides 30,000 miles (48,280 km) compared to 2,000 miles (3,200 km) from a Motorcycle Tire. Very cheap to purchase a car tire in comparison to a motorcycle tire.”

Cons of a Car Tire:

Motorcyle AccidentHandling & Safety: “A little harder to lean into turns (Sweeping Bends) and transition from left to right turning (flickability). However this didn’t require reducing speed as it was only a very minor difference.”

Fitting a Motorcycle Tyre

Fitting: “Motorcycle Tire Shop will not fit a car tire onto a motorcycle.

Motorcycle Tire Wear IndicatorWear & Cost: “Chain rubbing on car tire indicates the importance of selecting the correct width tire to allow clearance.”

Darkside Motorcycle Tally

Motard Squid Videos

Regular Rider (Maxim Honda)


Pros of a Car Tire:

Dark Side Motorcyle Tire Wear

Wear & Cost: “The tires are going to wear a lot quicker on a motorcycle than a car tire. This is because the compounds are a lot harder and stiffer on a car tire and on a motorcycle tire, they are a lot softer.”

Cons of a Car Tire:

Motorcyle Lost ControlHandling & Safety: “When a car tire turns it doesn’t lose much of its contact patch on the road as the suspension takes up the lean. With a motorcycle tire on a turn, due to its shape, you don’t feel the transition from the center of the tire to the edge. The transition is smooth and the tire grips. A car tire fitted to the rear of a motorcycle will lift the contact patch as it gets up onto the edge of the tire, whereas on a motorcycle tire it’s a smooth transition and you don’t lose much contact patch at all. It feels like you have lost control of the motorcycle as the car tire contact patch leaves the ground on a turn. On a wet or slippery condition, as the car tire contact patch leaves the ground on a turn, this could be a safety concern.”

Darkside Motorcyle Tally

Maxim Honda Video

Regular Rider (Chris Caliente)


Pros of a Car Tire:

“Not worth talking about as they are outweighed by safety and liability issues. You wouldn’t book a ticket to ride in an airplane running on kerosene to save money, you would choose the safer jet fuel option, why should it be different on a motorcycle?”

Cons of a Car Tire:

Motorcycle Safety Dark SideHandling & Safety: “The Owner’s Manuals contain a warning”:

Fitting improper tires on a motorcycle can effect handling and stability, that could cause a crash, in which you could be seriously injured or killed. Do not install car tires on this motorcycle.

“So from a safety and liability point of view, it is not smart or wise to put a car tire on a motorcycle, you will have your insurance claim denied and I would not teach a young person or new rider to put a car tire on a motorcycle.”

Dark Side Motorcyle Tally

Chris Caliente Video

Darkside Rider (Littlefoot7979)


Pros of a Car Tire:

Darkside Motorcycle Wear SavingsWear & Cost: “My car tire 195/55R16 for $63 will give me 40,000 miles (64,370 km) compared with $280 motorcycle tire to give me 2,000 miles (3,218 km) needing replacement twice a year. You have to add more cost for installation, due to more frequent replacement.”

Cons of a Car Tire:

Handling and Safety Motorcycle DarksideHandling & Safety: corners a little wierd, gets up on that edge, but 99% of my commute is being straight up and down, I don’t travel a lot of curves so it’s not a big deal.

Darkside Motorcycle Tally

Littlefoot7979 Video

Darkside Rider (D Redman)


Pros of a Car Tire:

Dark Side Motorcycle Contact PatchHandling & Safety: “Regular riders debate that there cannot be as much contact patch on a car tire, as there is on a motorcycle tire, because you’re leaning on a square edge. But you can see there is as much or even more rubber on the road, even on a hard turn, as there is on a motorcycle tire. Which, is demonstrated on my video.”

Darkside Tire Increased WearWear & Cost: “We give up a little of handling for increased wear.”

Cons of a Car Tire:

Motorcycle Falling OffHandling & Safety: “We give up a little of handling for increased wear.”

Dark Side Motorcycle Tally

D Redman Videos

Darkside Rider (Cash Storeone)


Pros of a Car Tire:

Motorcycle Handling & SafetyHandling & Safety: “Car tires are a little smoother, the rear brake works better due to more grip, handles great on the curves and superior traction in the rain due to less aquaplaning.”

Dark Side Tyre Wear SavingsWear & Cost: “Motorcycle tires are good for first 1500 miles (2,400 km), then the area in the middle is the first thing to wear out, they don’t wear evenly, whereas car tires wear evenly. My car 165/80R15 @ $57 wore out after 23,000 miles (37,000 km), whereas a motorcycle tire is only good for 6000 miles (9,600 km). Therefore, I can go on at least four 4,000 mile (6,400 km) trips and I have proved I can go 5, without worrying about changing a rear tire, so a car tire will last me 2 years.

Cons of a Car Tire:

Fitting Darkside Motorcycle TyreFitting: “Often difficult to seat the bead, 60 psi pressure should pop it in, 90 – 100 psi is the accepted average to get it to seat. Liberal amounts of Goop Hand Cleaner applied to the tire and rim greatly helps the seating of the bead. Leave tire in sun for a few hours to make it hot will also make it easier.”

Darkside Tire Tally

Cash Storeone Videos

Regular Rider (Motorcycle Intelligence)


Pros of a Car Tire:

Darkside Motorcycle Tire Wear and CostWear & Cost: “Motorcycle tires wear out faster than a car tires, so we have to check them more often for wear. Get rid of the motorcycle tires when they get down to the last 10%, most motorcycle tire failures occur in the last 10% and check air pressure weekly.”

Cons of a Car Tire:

Motorcycle Handling & SafetyHandling & Safety: Motorcycle rubber tire compound is softer which make it stick to the road better than a car tire.

Safety Tip: Be careful with new tires, whether motorcycle or car, the coating makes them a little slick and they will need a few hundred miles to wear them into the road to get adequate traction.

Darkside Rider Tally

Motorcycle Intelligence Video

Regular Rider (mkneebone)


Pros of a Car Tire:

Motorcycle Safety HandlingHandling & Safety: “In addition to the anecdotal data available on Internet forums, I personally know several long-distance riders who report only minor handling issues with car tires and zero tire failures over tens of thousands of miles.”

Fitting Car Tyre Motorcycle

Fitting: “There is a list of dealers reportedly willing to install car tires on motorcycle rims available at http://Darkside.nwff.info/?p=installersList
. If you do have your own tire mounting machine, mounting a car tire can be significantly more difficult than mounting a motorcycle tire. Because of the stiff sidewall, mounting a Run Flat tire can be particularly difficult. The Kumho 195/55R16 is much harder to mount on a Gold Wing rim than the  Dunlop Elite 3, which is hard enough.”

Cons of a Car Tire:

Darkside car tire handlingHandling & Safety: “There are a number of differences in the design of motorcycle and car tires that can affect the performance of the tire, but the most obvious is tread profile. Because of the difference in tread profile, a motorcycle doesn’t handle the same way with a car tire mounted on the rear. The flat tread of the car tire makes the bike want to stand back up after being leaned into a turn. More pressure on the  handlebars is required to keep the bike at the proper lean angle. In addition, depending on the shape of the transition between the flat part of the tread and the sidewall, it can be more difficult to make smooth transitions in lean angle as road curvature changes. Another handling-related issue with a car tire is that it requires noticeably more effort to hold the motorcycle upright when stopped on a road surface that slopes to the side. If the road surface is dropping to the right, the motorcycle wants to fall to the right. The “U” profile of a conventional motorcycle tire prevents this from happening. For the reasons described above, the use of car tires on motorcycles appears to be an incredibly bad idea.”

Fitting Car Tire on Motorbike

Fitting: “If you don’t have your own tire mounting machine, it can be difficult to find a shop to mount a car tire on a motorcycle rim. Many dealers don’t want the liability associated with mounting a tire that is clearly not approved for use on a motorcycle.”

Darksider Motorcycle Tally

mkneebone Video

Dark Side Car Tyre

Visit Iron Butt Association: Click Here

Darksider Opinion Tally

 

So after reviewing 4 Darksiders and 4 Regular riders, balancing the Pros and Cons of each subject, the score is even at 11 each.

 

Also, note that some regular riders had actually tried a car tire and that both sides were honest enough to supply both Pros and Cons for the Dark Side Car Tire concept. Well done riders.

You as the reader have been given a glimpse into both sides of the debate and can now make an informed decision to either continue as a Regular rider or to fit a car tire onto your motorcycle to try it for yourself.

Remember: Try not to judge others for having a different opinion, they feel as strongly as you do and have reasons that make them feel that way. Happy and safe riding, Darkside or Regular 🙂

Now I would like to share some videos of high speed, racetrack testing of car tires on motorcycles.

Riding K1600GTL with Darkside tire on the race track

Kumho car tire on the Goldwing on the race track

If you can run a car tire on the rear wheel, what about the front?


I will begin with my experience and the decision I made.

Wheelchair Sidecar Family

Motorcycle Sidecar Rear Tire

 

 

 

 

 

 

Because my 1990 FJ1200A does not lean, why do I run a Motorcycle tire on the front and a square profile on the rear? Well, I decided the sidecar car tire and rear motorcycle tire should match. So why did I not fit a square profile on the front. Simple, I took the advice of experienced sidecar enthusiasts. According to them, a square profile tire on the steerer, will follow every contour/groove on the road, in comparison to a motorcycle tire traveling straight. I have not tried a square profile on the front so I cannot comment on the difference personally. I just wanted to share why I chose the steerer I am running on my sidecar combination.

Darksiders that run Car Tires on the Front


Double Darkside (Car tires on both front and rear).

After watching the video above, I had a thought. It does appear that some car tires are “squarer” than others. If I were to select a car tire to run on my Honda Shadow, I think I would look for a tire with the most “roundish” shoulders. And if I were to fit a square profile on the front of my FJ1200A, I would do the same.

Car Tyre Shoulder
This tire looks like it has a “Quite Rounded” shoulder.

 

Important Tire Safety Tips


Tyre Safety

Motorcycle Darkside Car Tire Conversion – Car Tires that Fit Motorcycles


You can select the correct car tire for your motorcycle or help build the Darkside Tire Database by visiting the following website: Click Here

If you are reading this, then you have reviewed the videos and information above and should now have a good understanding of the Darkside and the pros/cons and safety issues from both sides of the debate.

Clearly there are benefits to the Dark Side. We would love to hear from you in the comments below, details and opinions from your experience on the Dark Side, and then you may like to read about an innovation that has revolutionized motorcycle steering, Motoinno TS3- Motorcycle Front Suspension Innovation.

Check out my other website, click the link below 🙂

Passive Income Academy Online Marketing

Haul N Ride website was created to explore Innovation and Human Creativity with a focus on Interesting, Rare and Unusual Motorcycles and Accessories. Haul N Ride welcomes the sharing of projects and ideas, creating an enjoyable and educational online resource. We like to hear from readers so please leave a comment below and let us know if this post helped you or if you have any questions.

Thank you for visiting Haul N Ride. Dave

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12 thoughts on “The Dark Side – The Love of Car Tires on Motorcycles

  1. Hi Joonya, thank you for visiting Haul N Ride and for your contribution to the comments. I am glad you said the word “properly” because it appears that many car tyres have been fitted to motorcycle rims and ridden across countries throughout the world. So it is physically possible, however, in your opinion they don’t seat “properly” to the bead. Here is another article on the subject with details of fitment to the rim. https://forum.ironbutt.org/index.php?threads/examining-the-%E2%80%9Cdark-side%E2%80%9D.9/
    Have a great day. Dave

  2. While generally a good article, it does get one thing wrong. Car and bike rims are slightly different to suit slightly different beads. It is actually physically impossible for a car tyre bead to properly seat on a bike rim.

  3. I had the same trouble when looking for a car tire for my FJ1200 after adding a sidecar. In my case, due to the difficulty in matching a tire, I chose to install a square profile vintage motorcycle tire.

    Your tire specs should be:
    Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
    160/80-16 5.0in 13.0in 26.1in 81.9in 773 0.0%

    My FJ1200 specs are:
    Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
    150/80-16 4.7in 12.7in 25.4in 79.9in 792 0.0%

    I installed this:
    https://www.antiquetyres.com.au/node/649

    As I cannot find our tires on this page: https://darkside.nwff.info/?p=tires

    I can only suggest you ask the question on one of the Dark Side forums:

    http://mcdarksiders.forumotion.com/t6050-2010-ultra-classic-first-ride

    http://forums.delphiforums.com/DarkSiding/start?gid=2126714059

    https://advrider.com/f/threads/darkside.308959/

    Good luck.

    PS: if anyone reading this can provide George the answer, please comment below. Cheers Dave

  4. What size car tire can I run on a 2006 Ultra classic .II it has a 160/80/16 no one makes store that size and were can I get t a tire that will work . Thank you

  5. Hi Serviceman, thank you for dropping by and sharing your valuable feedback of you experience with a car tire riding the dark side.

    I think the advice you provided regarding tire pressure will help a lot of other riders to get the best out of their setup.

    Also thank you for confirming that like Littlefoot7979 you also can get 40,000 miles from a tire.

    You raised a very good point. We should not judge others on their decision, just accept that we are all different and like different bikes. Have an awesome day and ride safe 🙂 Dave

  6. I have been riding on a car tire for 40000 miles. I have a kawasaki 2000cc. From experience on wet roads, riding in hard rain the car tire will grip the road better. It will hold up more weight, an harder to puncher If you where to have a puncher it will hold a repair where as you have to replace a motorcycle tire. There is difference in turning with the dark side. Also when riding on pot hole asphalt roads there is a difference. You do have to get use to riding with a darkside. Use less air in the tire than you would if the tire was on a car. I use 29 psi after breaking the tire in. I am running a triple tread good year. I ran 42 psi for 500 miles the dropped it to 29 psi. Try darkside and deside if it is for you. Everybody is different that is why we ride different bikes. When deciding what psi you like drop it 2 psi at a time until you find the sweat spot.

  7. Hi Brenda, thank you for stopping by and adding your comment. Considering you understand the dynamics of leaning and were used to leaning as a pillion, it is great to hear your feedback of the Dark-Sider experience as a passenger. I think your comment on use on highways is where Darksider would be an advantage for cost saving, however, even on a long trip you are still likely to enter and exit bends, sweeps and corners. It is important that you feel safe to enjoy the ride. Have a great day. Dave

  8. As a passenger only, I can only say that I was riding with my husband and really felt like something was different. I lean well considering my husband loves to lean on curves. But something seemed off. I felt like when we were leaning into a curve. I felt like while in the curve it was as if The bike was going to just fall over. I told the husband I thought something was different and he just scoffed. I really didn’t like the feeling. After some time, I just happened to hear a friend remark how do you like that car tire on the bike!! I couldn’t believe it!! So I promptly googled car tires on a cycle and had hubby read all about it!! So glad he listened and was willing to change that car tire the very next day. Maybe for straight long hiways but not for this passenger!!’

  9. Hi Nick, I am so glad that this article appeals to non-motorcyclists also. Now that you know about Darkside tires, I bet you will begin to notice bikes running car tires. Just like when you buy a car, you begin to notice that model everywhere. Thank you for your positive comment. Have an awesome day. Dave

  10. What a great article! I’m not a motorcyclist but I really learned a lot from this. I had no idea that you could even put a car tire on a bike rim. The visuals and pros and cons are really well thought out.

    Great work! I will be a regular reader.

  11. Hi Bobbi, I am glad you enjoyed the article. Yes I did endeavor to stay neutral to allow the riders the opportunity to provide their point of view. I would love to hear about your friends experience if your friend chooses to try Darksiding. I do not personally believe it to be unsafe, and when the rear tire on my two wheel motorcycle has worn out, I would like to try it too. Have an excellent day. Dave

  12. Wow, great article. I am not much of a motorcycle enthusiast but I do ride as a passenger with one of my dear friends. I am going to send him this website. I am sure he will take a look like you did at the darkside and the regular tires. I know that he uses regular tires now, but I have a feeling after watching some of these videos about pros and cons that he might at least give a car tire on the back a try. He is such a safe rider that I think he will be safe with a car tire , maybe not so square as the later videos shows on the back.
    Great post, loaded with information, and a great learning experience for me.

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