Car tire

Running a car tire on a motorcycle is commonly referred to as going to the "darkside". Owners of touring bikes have been using them for years. Typically, they cost about 1/2 the price of a motorcycle tire and last twice as long. It's commonly reported they give a better ride, are less suspectible to gravel, and offer more traction. On the negative side, some people say the bike will handle 'heavier' during tight turning and it is sometimes hard to find a place that will mount a car tire on a bike rim.

When a nail found my almost new 70-series tire (180/70-16) I put the old 60-series tire (180/60-16) back on. I liked the way the 70-series tire lowered the rpms on the highway, but I liked the way the 60-series made the bike feel 'lighter' (handled better and faster acceleration). I dismounted the 70-series tire via sawsall and tossed it in the junk pile.

Since I now had an extra rim I decided to give a car tire a try. A 195/55 car tire is similar in height to a 180/60 motorcycle tire, and a 195/65 is similar to the 180/70 tire. I decided to split the difference and try a 195/60 car tire. I found a Dunlop SP Sport 5000 (Ultra High Performance All-Season) in that size at for $114. Some people like to use run-flat tires but there none available in this size that I found.

The first thing I needed to do was get the tire mounted. I called a couple independent bike shops but they weren't interesting in mounting the tire. I decided to go by the local Honda shop the next day on my way to get my hair cut. They mounted and balanced it for $14.50. I fibbed a little and said it was for a trike, but the way the guy talked he didn't have any problem mounting it on a bike rim. He was well aware of bikes running car tires and he had no problem with it.

Changing tires on the Goldwing with its single-sided swingarm is easy:

1. Put the bike on the center stand.
2. Remove the license plate to expose a bolt.
3. Remove the rear fender (5 bolts, 5mm Allen).
4. Unbolt the cross brace (10mm socket). I also had to remove the center section of the Bushtec hitch.
5. Roll the rear tire out.

Here is the 180/60 motorcycle tire compared to the 195/60 car tire. The car tire is 5/8 - 3/4" taller and slightly wider.

The car tire is mounted. The only 'trick' I had to use was to let the air out to make the slightly wider tire more pliant. I put 32 psi back in it.

Initial impressions - I rode the bike in town to run a few errands. The car tire rides smoother. I did some tight turns in parking lots and didn't notice any negative handling. It helps the bike stay upright better at low speeds. I'll report more after I've spent some time with it.

One thing to report. The car tire generally tries to stay perpendicular to the road. When the road is off camber or uneven the car tire tries to follow the road and requires a little steering input, whereas a motorcycle tire will just roll on its side as in the above picture. It's not a huge deal, but it is a trait of car tires.

Update - Following some internet research I increased the tire pressure from 32 to 40 psi. It got rid of most of the 'following the road' feeling. It also lost a little bit of the smooth ride. I might try 38 psi in a few days to find the sweet spot for this tire.

Update 2 - After several weeks I've settled upon tire pressures of 34 front and 38 rear.

Update 2012 - I got 24,000 miles out of the first car tire. I will never go back. The car tire gives a smooth ride and has superior traction in rain, gravel, tar snakes, etc. I got a flat on our Georgia trip and the dealer put a motorcycle tire on. Hated it. The first thing I did when I got home was stick another car tire back on. I now run 32psi front and rear.

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