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Discussion Starter #1 (Edited)
Here is some information on the wheels size and offset for both models.

SlingShot SL:

Front Wheels 18X7.5 with +42mm Offset / 43.5 lbs with tires
Rear Wheel 20X9 with +45mm Offset / 53 lbs with tires

The SL's premium wheels are wrapped with 225/45R18 up front and 255/35R20 in the rear.

SlingShot Base:

Front Wheels 17X7 with +42mm Offset / 46.07 lbs with tires
Rear Wheel 18X9.5 with +45mm Offset / 57.07 lbs with tires

The Base gets 205/50R17 up front and 265/35R18 in the rear.

Lug nut Pattern is 5X114.3 for both

Keep in mind that while the size of the wheel is measured in inches, the offset is measured in Millimeters (mm).


What most people will look for is a wider rear tire... The main concerns with going with a wider rear are: keep the rear tire centered and not rub the swing arm...

So let's start with our center point. The rear offset is +45mm which is the center and keeps the wheel dead centered.
Ideally you will go for a wheel with +45mm offset...


The highest number (in my opinion) that you can go without noticing that the wheel is off the center is +/- 10mm

The higher the number of the offset the closer to the swing arm

The lower the number the farther out from the swing arm.


In other words:

+55mm will be 10mm closer to the swing arm (off center to the Right) Wheel cannot be too wide.
+35mm will be 10mm farther to the swing arm (off center to the left) Wheel can be wider.
 

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I wonder if it matters if the rim and tyre are perfectly centered ? With the right amount of negative offset you could mount a wider tyre but not infer with the belt and brakes . Just thinking out loud . sort of .
 

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The main question is how much distance space you have between the current wheel/tire and the hard parts.

The wider OEM18" rim/tire is 1.25" from the shock (1 5/8" from the swingarm) so accounting for tire deformation during cornering, wouldn't an 11" rim fit with no offset modification? The wheel/tire would be 3/4" closer.
 

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Here is some information on the wheels size and offset for both models.

SlingShot SL:

Front Wheels 18X7.5 with +42mm Offset
Rear Wheel 20X9 with +45mm Offset


SlingShot Base:

Front Wheels 17X7 with +42mm Offset
Rear Wheel 18X9.5 with +45mm Offset

Lug nut Pattern is 5X114.3 for both

Keep in mind that while the size of the wheel is measured in inches, the offset is measured in Millimeters (mm).


What most people will look for is a wider rear tire... The main concerns with going with a wider rear are: keep the rear tire centered and not rub the swing arm...

So let's start with our center point. The rear offset is +45mm which is the center and keeps the wheel dead centered.
Ideally you will go for a wheel with +45mm offset...


The highest number (in my opinion) that you can go without noticing that the wheel is off the center is +/- 10mm

The higher the number of the offset the closer to the swing arm

The lower the number the farther out from the swing arm.


In other words:

+55mm will be 10mm closer to the swing arm (off center to the Right) Wheel cannot be too wide.
+35mm will be 10mm farther to the swing arm (off center to the left) Wheel can be wider.
Hi XXX,
Thanks for Information!
I too want wider wheels and tires however, I measured 1 1/2" clearance from swingarm to wheel/tire combo. How much tolerance would I need for the NEW wheel/tire to safely function without compromising the space between wheel and swingarm?

Are you saying +10mm is the max increase you can go (NEW wheel/tire) from the existing wheel/tire to function safely WITHOUT the possibility of rubbing swingarm?
 

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I'm pretty sure that is max out on wheel size if you want the wheel to be centered. You can go wider but it will not be centered.
 

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Discussion Starter #8
Hi XXX,
Thanks for Information!
I too want wider wheels and tires however, I measured 1 1/2" clearance from swingarm to wheel/tire combo. How much tolerance would I need for the NEW wheel/tire to safely function without compromising the space between wheel and swingarm?

Are you saying +10mm is the max increase you can go (NEW wheel/tire) from the existing wheel/tire to function safely WITHOUT the possibility of rubbing swingarm?
No. What I am saying is the +/-10mm is the largest offset change without noticing that the wheel is off-centered.

It all depends on how radical you want to go.
You can easily mount a 12 inch with +35 offset and still have clearance. it will be off centered by 10mm. and you will have around 1/2 inch clearance to the swing arm.

However, if you find wheels that have a 45mm Offset then the wider you can do is 11.

If your wheels are +55mm offset then 10.5 inch.

I hope that helps !
 

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So what size rear tire do you recommend on the SL once I rip through this stock one? Keeping the SL wheels...
 

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Discussion Starter #10
So what size rear tire do you recommend on the SL once I rip through this stock one? Keeping the SL wheels...
i would keep the same size... Going wider reduces the tire walls strength. Going smaller - well, nobody does that !

What I do not like about the SL wheel is that is only 9" wide...

Polaris take note...
 

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i would keep the same size... Going wider reduces the tire walls strength. Going smaller - well, nobody does that !

What I do not like about the SL wheel is that is only 9" wide...

Polaris take note...
Now I just need to keep reading about which brand to choose
 

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Discussion Starter #12
Now I just need to keep reading about which brand to choose
That is a very delicate topic...

I posted some information on another thread discussing Specifically the aftermarket wheels and how to be careful when selecting wheels.

But this sums it all...

Once upon a time those after market wheels were very pretty..








Check the clips out and continue doing your own research...

Just ask your self a simple question: which wheels are being used on the track? which is probably the highest abuse the wheels will take... I tell you this much; you won't see Forgiato at the track...

My Personal wheels of choice: ADVAN Racing and RAYS Engineering.
 

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i would keep the same size... Going wider reduces the tire walls strength. Going smaller - well, nobody does that !

What I do not like about the SL wheel is that is only 9" wide...

Polaris take note...

This is a question, not a statement, since you cannot hear my intent in type I though it necessary to clarify. ;)

With my background being bikes I wonder if those wanting wider wheels and tires or a wider wheel to tire width ratio have considered that the rear of the SS leans, or maybe more correct, rolls in turns. Its rear tire dynamics seem to be more like a bike than a car. Going by bike standards I would fully understand why they chose the wheel and tire width combination they did and how a wider wheel may add stresses to the single sided swingarm and force the rear tire to cantilever further when it transitions to the edge of the tire in a turn, making the contact patch smaller even though the wheel and/or tire is wider. In my mind a wider tire with all other things equal would be better for straight line work and (for some) looks, but may cause handling issues and loss of grip in the twisty bits. Might be totally in left field here but from my perspective it makes sense .....

An extreme example, and yes I understand the SS does not lean this much :

 

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The main question is how much distance space you have between the current wheel/tire and the hard parts.

The wider OEM18" rim/tire is 1.25" from the shock (1 5/8" from the swingarm) so accounting for tire deformation during cornering, wouldn't an 11" rim fit with no offset modification? The wheel/tire would be 3/4" closer.
 

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This is a question, not a statement, since you cannot hear my intent in type I though it necessary to clarify. ;)

With my background being bikes I wonder if those wanting wider wheels and tires or a wider wheel to tire width ratio have considered that the rear of the SS leans, or maybe more correct, rolls in turns. Its rear tire dynamics seem to be more like a bike than a car. Going by bike standards I would fully understand why they chose the wheel and tire width combination they did and how a wider wheel may add stresses to the single sided swingarm and force the rear tire to cantilever further when it transitions to the edge of the tire in a turn, making the contact patch smaller even though the wheel and/or tire is wider. In my mind a wider tire with all other things equal would be better for straight line work and (for some) looks, but may cause handling issues and loss of grip in the twisty bits. Might be totally in left field here but from my perspective it makes sense .....

An extreme example, and yes I understand the SS does not lean this much :

All things being equal you will get more contact patch in all situations with a wider tire. Not sure where you are going with cantilever forces especially since load, force, and fulcrum point don't change relative to each other (assuming you use the same offset wheel). If anything cantilever is reduced because force is farther away from the point of fulcrum - it's easier to push an 8" wide wheel over vs. an 11" wide wheel (same diameter).

The interesting handling characteristics will be what happens when you don't change the wheels/tires in the same way front to back. For example, putting a stickier, wider tire on the rear will force the front end push/understeer a lot more. Also, adding grippier front/rear tires will increase the likelihood of raising the inside front tire while cooking it into a turn. Stiffer suspension/thicker swaybar will be needed to counteract it or maybe going less offset on the front to push the tires wider in front - if you dare (my garage opening is tight already ;) ).

It will be interesting to see firsthand once the weather warms up here in the northeast.
 

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All things being equal you will get more contact patch in all situations with a wider tire. Not sure where you are going with cantilever forces especially since load, force, and fulcrum point don't change relative to each other (assuming you use the same offset wheel). If anything cantilever is reduced because force is farther away from the point of fulcrum - it's easier to push an 8" wide wheel over vs. an 11" wide wheel (same diameter).
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If the rear had a suspension that was working to keep the contact patch level with the road surface I could understand but it doesn't. The rear suspension moves as a unit with body roll, same as a bike, so with a flat profile tire the contact patch changes relative to its angle. I do think you agreed with me without meaning to that a wider tire is naturally harder to transition from side to side so would put more twisting stress on the rear swingarm and hub. If it reacts more like a motorcycle it would also be slower to respond and the wider you go the more abrupt the transition will be.

Yes sir, it should be interesting to see where this all leads, with no real information base it is all new even to those well versed in their respective fields. Exciting times.

.
 

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If the rear had a suspension that was working to keep the contact patch level with the road surface I could understand but it doesn't. The rear suspension moves as a unit with body roll, same as a bike, so with a flat profile tire the contact patch changes relative to its angle. I do think you agreed with me without meaning to that a wider tire is naturally harder to transition from side to side so would put more twisting stress on the rear swingarm and hub. If it reacts more like a motorcycle it would also be slower to respond and the wider you go the more abrupt the transition will be.

Yes sir, it should be interesting to see where this all leads, with no real information base it is all new even to those well versed in their respective fields. Exciting times.

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Oh yes, I do agree that there are additional stresses to the hub/swingarm though thats what gets translated into better adhesion. It's akin to using a thicker swaybar - it will produce a lot more stress on the suspension but gets translated into better traction. I think with a wheel that is, say, an additional 1.5" wider, the stresses will be minimal. Remember that the center of gravity is at the base of the shift lever so it would take a lot of roll angle to have a large impact on contact patch - as the motorcycle example illustrates. Having the CG height nearly at the center of the wheel definitely helps.

Do note that most of the SSs that were in the press shots always had the outside of the rear tire balding first. I am curious to see if it is any better with a wider tire. I will be going to an 11" wheel with a 305 section tire when the weather gets better. I also plan to widen the front tires the same percentage (to roughly a 245 section tire) to hopefully keep the handling characteristics the same but just raise the limits.

I will probably use less offset on the fronts to push the tires out a bit (maybe 10mm) and yes, that will also produce more stress on the existing parts but produce more adhesion in the corners while keeping both fronts on the pavement longer. Hopefully by using lighter wheels, I will be able to offset the additional cornering force with some reduced unsprung weight. Damn this cold weather!
 
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