I`m designing a vehicle with 2 wheels in front and one at the rear. A motorbike engine will
be driving the single rear wheel. I`m planning to use car wheels also at the rear(the rear fork
will be single sided, like some motorcycles have).

My guestions is, how much wider should the rear tire be than the front tyre(s)?

The new Suzuki VZR 1800 intruder custom bike has a rear tire in size 260/40R18. Could that kind
of bike tire installed on 18" car wheel? Do you think it would be worth considering instead of car tyre?

Metzeler: 260/40 VR 18 M/C (84V) TL ME 880 MARATHON

I dont think you could install a bike tyre because of the way it is formed (the tyre is arched) unless the vehicle is going to lean over in cornering. I should think a car tyre should be fine. As for width, not sure on that one but i personally think a slightly wider wheel/tyre looks better on trikes

I'd take "inspiration" from someone who's designed a car like that before. If you follow these links, you'll find the tyre specifications of these two 3 wheelers.

The Malone Skunk:-


http://www.malonecar.eclipse.co.uk/

Or the Grinnall Scorpion:-



http://www.grinnallcars.com/content/home/home.html

Good luck with the project, and keep us updated!

HTH

Mike

as above, bike tyres should only be used for vehicles that lean. Otherwise you will have very little grip, very little stopping power and huge & expensive tyre wear compared to using a correct car tyre

A bike tyre will wear a flat and once it's down to the marker it's illegal even if it's only the bit in the middle. If you're using a bike swing arm you could look for one with a 17" rim and probably save a bit on tyre price.

Mine's going to MSVA with the original scooter tyre on the back. Once it wears, I'll probably fit a car tyre.

For the same overall width, a car tyre will have a wider patch of rubber on the road. Potentially more dry grip but perhaps more aquaplaning.

My calcs show my 3 wheeler will have the same weight an the rear tyre when 2 up as the donor would have two up. If the original had enough tyre on the road, so will mine.

As above, fit a car tyre. A bike tyre as stated is designed to lean, and if its used on a car that essentially doesnt, will wear out in no time flat.

The setup of those grinnali and malone is exactly what I`m planning.

Would it be a good idea to incorporate a relatively stiff roll bar to the front suspension? I`m afraid that the
vehicle would oversteer because there`s only one rear wheel and therefore less traction. When the body rolls it
gets even wore. The angle in which the rear tire meets the ground, is exactly the same as the body roll angle.
In the front suspension the change is not so great because of the suspension geometry. This should mean that the
vehicle oversteers more and more when the roll angle increases. The roll bar in front would help keeping the body
straight and also would reduce traction on the front axle like is commonly know.

Sounds good at least in theory. Tell me if I`m wrong.

I took my Piaggio scooter rear wheel to have a car profile tyre fitted for my three wheeler.
The tryre fitters could not get the tyre to pop out on to the rim.
we came to the conclusion that the wheel rim was too big even though the rim is marked as 14 inch the same as the car tyre.
Any idea's anyone?????????
Regards Denis,

Without any doubt, a car tyre