Performance Tires For The Elio Will Be A Pain.

[DeltaMike]

I believe you have it backward Wizard. 135/80/R15 tires are the fronts. 175/65/R15 for the rear. Slightly wider for a little larger contact patch since there's only one. These are more than adequate for a daily driver. A lightweight vehicle like the Elio would hydroplane easily in heavy rain (like we have regularly in the Houston area). Wider tires would only exasperate that. You could end up with a vehicle that would be undriveable at anything over 25 or 30 mph.

Skygazer, I agree with your general premise that messing with the tires could be consequential. However, I believe the predominant factor in theoretical dynamic hydroplane speed is tire pressure. DHS in mph is about 10 x sq root of tire pressure in psi. Merely underinflated tires will hydro at a lower speed. So I agree with where I think you get to in that IF the skinny standard tires are higher pressure versus lower pressure low profile aftermarket tires, the theoretical hydro may be reduced with a resulting increased risk.
What I don't know is the psi of the standard front tires.

 

[TeamCoconutOreo]

I agree! EM has done a lot of research/testing before deciding what sizes to use, to make sure the Elio will handle in a safe and predictable manner, in all driving conditions. I have little doubt that there will be some who throw on bigger tires with intention of better handling, like for Auto-cross. But, Is Auto-cross ever done in the rain? Or Snow? Or with a child in the vehicle? Or around pedestrians? I know there are people out there who like to "modify" everything!..I am one of them. I just hope we can do it in a safe and responsible way. I would hate to see Elio get a reputation like the Corvair (unpredictable over-steer), just because a bunch of folks "thought it was a good idea" to put on the "same size tire front and rear." Time for my meds.

I'm pretty sure Elio's is likely stretching the envolope for hyper mileage and not cornering. I have never owned a vehicle I did not change the tire width on. I've never had a mechanical failure or a hydroplaning issue. The 2.5 to 3 inch difference is negligible, the real difference is tire compound. You give up some smoothness, tire life and MPG for a grip.

 

[CrimsonEclipse]

I believe you have it backward Wizard. 135/80/R15 tires are the fronts. 175/65/R15 for the rear. Slightly wider for a little larger contact patch since there's only one. These are more than adequate for a daily driver. A lightweight vehicle like the Elio would hydroplane easily in heavy rain (like we have regularly in the Houston area). Wider tires would only exasperate that. You could end up with a vehicle that would be undriveable at anything over 25 or 30 mph.

Hydroplaning is actually a factor of tire PSI.

The formula is generally 9.9 x (the square root of tire PSI) = hydroplaning speed in MPH

Wider tires means a larger contact patch which means a lower proper PSI inflation.

This can be mitigated in part by tread design and materials.

The car's weight is supported by the tires. Calculate the tire patch area (the area where the tire actually touches the ground) and you can calculate the PSI required to support the weight.

If the tire patch is, for instance 4" x 3" = 12 square inches x 36 psi = 432 x 3 wheels = 1296 lb

Increase the width by 1" to 4" x 4" = 16 square inches x 27 psi =432 x 3 wheels = 1296

Hydro planing changes: from 59.4 MPH at 36 psi to 51.4 MPH at 27 psi.

 

[Ty]

Hydroplaning is actually a factor of tire PSI.

The formula is generally 9.9 x (the square root of tire PSI) = hydroplaning speed in MPH

Wider tires means a larger contact patch which means a lower proper PSI inflation.

This can be mitigated in part by tread design and materials.

I think you guys are mixing up PSI as a tire pressure vs. PSI as the pressure the tire exhibits on the road... Example... a REALLY heavy dump truck on wide tires won't hydroplane as much as a Mazda Miata on the same wide tires... Hydroplaning is a factor of contact patch and weight per inch of contact patch... PSI. Tire inflation isn't a consideration in that calculation. Now, IF you were to deflate a tire and thusly increase it's contact patch (not a guaranty that it wouldn't decrease the contact patch but that's another conversation), your car's weight stays the same but now the PSI that the tire has to the road is lessened which increases the likelihood of hydroplaning (floating across the road on a film of water).

 

[CrimsonEclipse]

I think you guys are mixing up PSI as a tire pressure vs. PSI as the pressure the tire exhibits on the road... Example... a REALLY heavy dump truck on wide tires won't hydroplane as much as a Mazda Miata on the same wide tires... Hydroplaning is a factor of contact patch and weight per inch of contact patch... PSI. Tire inflation isn't a consideration in that calculation. Now, IF you were to deflate a tire and thusly increase it's contact patch (not a guaranty that it wouldn't decrease the contact patch but that's another conversation), your car's weight stays the same but now the PSI that the tire has to the road is lessened which increases the likelihood of hydroplaning (floating across the road on a film of water).

Remember, water is (relatively) not compressible, it can be displaced though (which is a factor if viscosity, not weight).
It doesn't care about weight (unless you're talking about millions of tonnes)

 

[WilliamH]

Remember, water is (relatively) not compressible, it can be displaced though (which is a factor if viscosity, not weight).
It doesn't care about weight (unless you're talking about millions of tonnes)

You can probably do something with the front tires.
The rear tire will be your problem.
It's on a swing arm which would force an offset to the left side with a wider rear tire.
I think that would throw off the geometry and cause alignment problems.

 

[wizard of ahs]

You can probably do something with the front tires.
The rear tire will be your problem.
It's on a swing arm which would force an offset to the left side with a wider rear tire.
I think that would throw off the geometry and cause alignment problems.

I think a wider wheel would, but I'm not sure about a wider Tire?

 

[booboo]

I just noticed the P3 had fairly wide tires back then.

 

[CrimsonEclipse]

You can probably do something with the front tires.
The rear tire will be your problem.
It's on a swing arm which would force an offset to the left side with a wider rear tire.
I think that would throw off the geometry and cause alignment problems.

The rear tire can be made wider but a custom wheel would likely be needed to counter the offset.
The rear tire will also experience the widest range of loads. The front load is relatively constant, there will always be a driver and always have an engine and transmission. The passenger seat is almost directly over the tire so the addition or subtraction of a 50-250lb passenger will directly change the load on the rear tire and possibly the driving characteristics.

 

[airforceguy6]

The rear tire can be made wider but a custom wheel would likely be needed to counter the offset.
The rear tire will also experience the widest range of loads. The front load is relatively constant, there will always be a driver and always have an engine and transmission. The passenger seat is almost directly over the tire so the addition or subtraction of a 50-250lb passenger will directly change the load on the rear tire and possibly the driving characteristics.

Hi Crimson, I agree that a passenger will change the characteristics of driving, just like it does on a motorcycle when you have a passenger. However, the passenger is not directly above the wheel and suspension system, they are in front of it. So my guess would be that it will have some effect, but not necessarily significant.

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