Some people with big cruisers like Goldwings are installing car tires on their bike.
Is hat a good idea?
First this is illegal in some countries and your insurance may not cover you in case of crash.
82gl1100iWingman posted on goldwingfacts.com a very good article about design differences between car and motorcycle Rim/Tire.
Read the full post here

People used to use Citroen 2CV tire on their Outfits, many years ago.

Can't remember the exact details, but it seemed to work!

I am using the same type of tires on the outfit. Citroen 2cv or old VW beetle. They use the same type of tires (135 or 145 R15). 
The rims on the outfit are car types and not MC.
An outfit reacts a bit like a car. You don't lean (or very seldom). The sidecar frame doesn't have any flexible anchor points and is part of the bike's frame.
The problem is with people using the original MC rims/car tire on the back of a solo bike. This is quite common here in NA.

I always knew that car tyres wouldn't fit on motorcycle rims, but that's the first real technical explanation I've seen as to why. I also knew that the car tyre tread pattern wouldn't deform in the same way as a motorcycle tyre (logical, that!). Anyone who's ever fallen off the tread on an Avon Speedmaster MkII wouldn't go anywhere near a car tyre anyway. IMNSHO - damn stupid idea.

There are 17" car tyres that will fit 17" bike wheels.

I've got 15" wheels front and rear on the sidecar, I have a 165/80-15 rear car tyre and though I can fit a car tyre on the front (typically 135, 145 or 145/65) I prefer a bike tyre, either 130/90-15 or 140/80-15.

A friend who had a Triumph Rocket 3(solo) used to run car tyres on the rear sometimes. In his case he was experimenting as many of his customers were doing it and he didnt want to comment without experiencing it himself.  He was a Triumph dealer, in the end he though they were fine.

Al

Yes its quite quirky really but the deal is its going to void insurance. The fact that they fit though not technically a true fit due to the different types of seat, hasn't stopped many from doing it and reporting they get phenomenal grip and distance on them.

All it takes is one instance and a policeman to note the tyre not fit for purpose, on a report and in most states here you are sunk. Then you run into trouble. Insurance wont pay out, the other party to the incident then claims you should not have been there in the first place, the whole thing escalates to a point where some would wonder if it was indeed a good idea.

60 year ago, it would be fine. I reckon many are too litigious these days. Disappointing isn't it.

Al, I guess that you have car rims front and rear? Or just the rear? The guy I went to India with builds outfits. The last one he made he machined a Smart car wheel to fit an R100RS rear hub (or the other way round!). The rig runs car tyres on the sidecar and bike rear and a bike tyre at the front. UK legal, because he's using the correct rims.

From the little I understand, a bike tyre is better up front because it makes the steering easier. I can figure out why but I'm stymied when it comes to try and write it down!

Dai wrote:Al, I guess that you have car rims front and rear? Or just the rear? The guy I went to India with builds outfits. The last one he made he machined a Smart car wheel to fit an R100RS rear hub (or the other way round!). The rig runs car tyres on the sidecar and bike rear and a bike tyre at the front. UK legal, because he's using the correct rims.

From the little I understand, a bike tyre is better up front because it makes the steering easier. I can figure out why but I'm stymied when it comes to try and write it down!

Smaller contact area on the road, harder to turn bigger contact area at low speeds, plus increase in rolling resistance?

Back when cars generally did not have power steering if you went up a tyre size as one would the first thing noted was heavier steering.

Dai wrote:Al, I guess that you have car rims front and rear? Or just the rear? The guy I went to India with builds outfits. The last one he made he machined a Smart car wheel to fit an R100RS rear hub (or the other way round!). The rig runs car tyres on the sidecar and bike rear and a bike tyre at the front. UK legal, because he's using the correct rims.

From the little I understand, a bike tyre is better up front because it makes the steering easier. I can figure out why but I'm stymied when it comes to try and write it down!

The front and rear are custom 15" wheels, not car wheels on adapters. The rear always runs a car tyre between 135-165 wide.  155 is a nice size for width/height and slight reduction in gearing but is hard to get. 165 is the easy choice in Australia, 135 makes the engine rev too hard at speed and breaks away more easily under power (one tyre I had shredded rather than wore out)

The front wheel; I don't know whether it was made to car or bike specs.  Bike tyres always fit easily, a 135 or 145/80 car tyres fit easily, a 145/65-15 Smart car tyre is an absolute bitch and takes over 70psi to make it seat on the bead, never mind getting it off.

Smart car tyre: bigger contact patch, better brakes, sharp handling(low profile), better high speed.  Heavier steering, more inclined to head shake.

Bike tyre (130 or 140), smaller contact patch, brakes not as good more inclined to lock the front, less confident in wet conditions (ie must ride slower).  Lighter steering, very little head shake(due to narrower contact patch), I'm not even running a steering damper now.

With the state of my shoulders at the moment, the lighter steering wins the argument for me at the moment.  I did run a car tyre up front for many years and I do understand why you would, each is a compromise with their own strengths.

Al