My experience with lightweight wheels

[royanddoreen]

I've shed 71lbs with my wheel tire setup and I love all aspects of the change.Wheels are 1" narrower then stock, air pressure same, and coasting is even better. I remember putting 7" wide wheels on a civic and it changed the camber of the suspension,making the rear tires wear on the inside edge, can't remember if coasting was affected. No doubt the width has a big effect in the rain,Narrow is the way to go for fuel economy. Looking to hear more about your efforts RPM,,Roy.

[Cobb]

I got new 10mm wider tires, but no diff. Now on the old ones I notice the right side wanted to hydroplane. I checked and the tread was more worn than the drivers side.

Now wider rims spreads the tire out more, if they are fully inflated to sidewall psi the tire may not of had the same contact with the road. There is a limit to tire vs rim width and how you mix and match them.

[redpoint5]

After reading through this thread a second time, I'm doubtful the loss in hill-climbing ability had much to do with less momentum in the wheels. How much extra stored energy is there in 2.8 kg heavier wheels? It must be small, and would quickly be consumed by a sustained hill climb.

I suspect something else is going on here. Keeping the same tire on a wider wheel affected something in a negative way, be it toe, camber, or perhaps aerodynamics. In theory, using the same tire on a wider wheel would reduce the overall circumference. This would effectively make for a lower gear ratio and should improve hill climbing ability.

The first thing I would do is have the alignment checked, as I believe that would be the most likely thing that would explain the noticeable loss in coasting and hill climbing. Next I would measure the same tire mounted on both size wheels. Who knows, maybe something strange is going on, and it's changing the effective gearing of the vehicle. Is it possible the lower "gearing" of the tires is allowing the car to maintain a higher actual gear on the hill, which makes it feel less powerful while going up said hill?

All other variables held constant, lighter weight wheels would climb a sustained hill quicker than heavier wheels. The problem is that you haven't held all other variables constant (changing wheel width and tire profile). One of those other variables is causing your problem.

...and it's no surprise that a wider tire handles poorly in the rain. I find hydroplaning to be fun and exhilarating, but I can understand why sane people would prefer to avoid it.

[RPM]

If I accelerate up the hill the car responds well, better than before (i.e. WOT performance has improved). If I DWL up the hill though, it looses a lot of speed. It might have to do with the lean burn capabilities this motor has. Perhaps with the heavier wheels the load on the engine was higher, causing the engine to enrich the mixture and hence produce more power (this is just a theory).

Fortunately I didn't experience any aquaplaning yesterday, I just felt the car's progress being noticeably hindered by the water (poor coasting, more accelerator needed to maintain speed). Fortunately the tires (Michelin Pilot Exalto 2, they are sports summer tires) still have roughly 5 mm of thread and grip very well in the wet.

I will check my alignment though, thanks for reminding me. It's been maybe 20.000 miles since the last time I had it done.

Unfortunately it is impossible for me to do scientific testing of such things. I don't have the budget to buy multiple sets of wheels and professional tools to properly isolate and evaluate the variables at stake.

[Phase]

How is highway mpg affected? I keep hearing some say gas mileage still increased but to a smaller percent because you’re still rotation lighter wheels but others have said the momentum and inertia are affected so now it takes more energy to keep the car going at a constant speed

[freebeard]

RPM
EcoModding Lurker
Last Activity: 06-14-2021 02:36 PM

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[RPM]

Hello there! It was with great surprise that I received an email warning me there was a new reply to this almost decade-old thread. Time really does fly!

Originally Posted by Phase

How is highway mpg affected? I keep hearing some say gas mileage still increased but to a smaller percent because you’re still rotation lighter wheels but others have said the momentum and inertia are affected so now it takes more energy to keep the car going at a constant speed

It's been too long for me to remember this well. But, if I'm not mistaken, highway fuel efficiency took a very small hit with the lighter wheels, due to poorer coasting.

In practical terms I loved the car's handling so much I kept them on until I sold the vehicle in 2018.

Such a neat car. It was immaculate. This made me nostalgic. I'm not even in the same country anymore.

[freebeard]

Two hour response time is good after a decade. So -- not-Portugal?

[Phase]

Originally Posted by RPM

Hello there! It was with great surprise that I received an email warning me there was a new reply to this almost decade-old thread. Time really does fly!



It's been too long for me to remember this well. But, if I'm not mistaken, highway fuel efficiency took a very small hit with the lighter wheels, due to poorer coasting.

In practical terms I loved the car's handling so much I kept them on until I sold the vehicle in 2018.

Such a neat car. It was immaculate. This made me nostalgic. I'm not even in the same country anymore.

wow impressive on the reply. thanks for the info regarding highway mpg. im trying to configure the best mpg for a 2024 prius and want maximum highway mpg and was trying to see if lighter wheels help or hurt

[RPM]

Originally Posted by Phase

wow impressive on the reply. thanks for the info regarding highway mpg. im trying to configure the best mpg for a 2024 prius and want maximum highway mpg and was trying to see if lighter wheels help or hurt

For highway fuel economy honestly you're better off keeping the stock wheels. Lightweight ones won't help on that particular front.

If you want to mod you could install some moon disks. Aero improvements will have the largest effect at highway speeds. Loosing weight helps with city driving.

Originally Posted by freebeard

Two hour response time is good after a decade. So -- not-Portugal?

Right. I now spend most of my time in the US.