Can any of the reverse-trike intellectuals give an opinion on rear-tyre sizes?

A super-fat rear (300+) would indeed look cool, but what would the effect be on the machine, say in contrast to a more normal 190 size?

Ta!

Is it going to lean? a fat tyre will resist leaning.

Also depends on the weight over that wheel, less weight thinner tyre otherwise the contact pressure will reduce, ok in the dry because you have a greater surface area in cotacct with the road, but would be bad in the wet.

Is the rear wheel going to be driven?

Assuming a driven rear-wheel and minimal leaning (traditional wishbones at the front and vertical rear swing-arm travel)

Take the lowest tyre pressure that the side walls will cope with and divide by the weight on your rear wheel. This will give you the biggest size of your contact patch. Divide that by the width of your tyre and that will give you the length of your contact parch. Now think about aquaplaning where the front few centimetres of tyre are lifted off the ground by water. Do you have any grip left? That's not to mention traction on such a thin contact patch.

The other thing you need to consider is the balance of grip between front and rear. Do you want permanent understeer? I would suggest a wider tyre at the rear than the two fronts but not too wide.

quote:

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Originally posted by smart51
Take the lowest tyre pressure that the side walls will cope with and divide by the weight on your rear wheel. This will give you the biggest size of your contact patch. Divide that by the width of your tyre and that will give you the length of your contact parch. Now think about aquaplaning where the front few centimetres of tyre are lifted off the ground by water. Do you have any grip left? That's not to mention traction on such a thin contact patch.

The other thing you need to consider is the balance of grip between front and rear. Do you want permanent understeer? I would suggest a wider tyre at the rear than the two fronts but not too wide.

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Can be made to work (you need a car tyre not a bike tyre unless you are leaning).

Given the conditions the t-rex can get it down the power down pretty well through its big rear tyre.
http://www.youtube.com/watch?v=OpkVzH1ltw0

Cheers guys... not so much concerned about wet-weather performance TBH.

Go wide its cool on a trike.

All the roll resistance is taken by the front tyres so go wide there too.

Crucial to keep the c of g low, or more correctly the overturning moment low so a wide front track would not only look good but would be functional.

Bikes tend to have a high c of g so just grafting a bike back end on to a locost front may not get the best results.

Tempting project but when would you use it?

a nice big fat 17 or 18" car wheel with low profile tyre

at least running car tyres its far cheaper than a bike one!

I`m also building a trike with one rear wheel. There`s a chain drive from a motorbike engine and the rear swing-arm is single sided. Then I can use a car wheel in the rear also.

There are some problems if I want to have a wide rear wheel. The first is, the engine has to be installed off center if the rear wheel is considerably wider than in the motorcycle the engine is from. The chain would otherwise collide with the tire on the left side. Moving the engine off the center affects the weight distribution negatively.

In front I would like to have reasonably small and narrow wheels, not least because the vehicle is lightweight, so have the wheels have to be also lightweight. Ideally the front wheels and the rear wheel should look the same, except the rear wheel being wider. For front I have been considering 195/50R15 or 195/45R16 with either 6,5” or 7” wide wheel. There`s wide range of nice looking wheels available in these sizes and also the tires are inexpensive.

In the 15” or 16” there aren’t much more wider wheels than 7”. If you want wider, you have go to larger diameter also.

18x8 for example is quite common size, it would allow to mount max 245/40 tyre. I have found a coupe nice wheel types which have sizes from 6,5”x15” to 18”x8”. So it would be some sort of compromise.