My Konig Helium experiment (2 sets of Heliums with different tires)

Hey guys and gals. So last week Home - Discount Tire Direct lost their mind and did some ridiculous rebates on wheels and tires. I lost my mind as well and bought 2 sets for my brand new 2015 Prius C!

We all know by know that the Konig Helium weighs 11.4lbs plus an additional few oz. for the valve stem, ceter cap and clip, and any needed wheel weights (approx 5lbs less than the OEM steel wheel).

-One set in bronze with 195/55/15 Hankook Ventus V2 Concept tires that weigh 16.6lbs each, total 28lbs 2.8oz ($365 after all rebates rims and tires).

-One set in silver with 175/65/15 General Altimax43 tires that weigh 2lbs less @ 14.6lbs each ($427 after all rebates rims and tires).

-For reference, stock wheel with 1k miles and tire with cap pictured below @ 32lbs 13.6oz. Best I can tell, my research has the stock tire (Bridgestone Turanza EL400) weighing 16.3lbs and the stock wheel is 16lbs+ and the hub cap is 14oz.


Prices were mounted, balanced, free ship, no tax with hubcentric rings. =)

Well, the bronze set just came in today and I got the chance to mount them up and take the car for a quick spin. In short, the car sticks like glue now! OMG, I really was not liking the slding around the OEM tires were doing. I mean seriously? 4 wheel unintentional drifts while taking turns at or near the speed limit? I was fearing for when my 14yr old daughter starts driving in a few years and started having visions of her driving right off the road! Car also accelerates notably better with the combo of 4.5lbs less rotational mass per corner and the slightly smaller diameter. My theory is that the mpg penalty due to non LRR and wider tires will be minimal and mostly offset by the lower weight rims/tires. My other set coming in with stock size tires will demonstrate just how much better your mpg can improve with a lightweight setup.

Ok, so no mileage to report yet, but I will be updating this thread as I get the other set with the stock size tires on. That should give me a real good feel for what lightening the wheels and tires by 6.5lbs (on stock size tires) per corner can do for MPG. I will also update over time with the difference in MPG with the wider tires for comparison and adjust for tire diameter size in my calculations. (stock is 23.96" 195/55/15 is 23.44" diameter...2.14% smaller).

One last note for the tech savvy guys still reading...this wheel has about the perfect amount of "poke" relative to the fender with the 195 tires. Any more, and it is really going to start disrupting airflow up front. I had thought about the 3/4lb lighter Advanti racing S1 Storm wheels in a 15x7" size but they also had a slightly more aggressive offset. Had I have gone that route with a 205/55/15 which would have put me at 24.1" diameter, the wheel would have stuck out another 10mm more than this setup and might have started to look funny. Also of interest is that there is not a lot of space for running a spacer with these short lug studs. A 3mm spacer would be max without having to change the studs. Some may want to run a spacer for aesthetics as the rear wheel is tucked in further from the fender than the front wheel. Others who run a wider/taller tire on a different rim may need one to prevent rubbing.

-Also of interest to some is that I saved 1.3oz per wheel with the aftermarket "open end" lug nuts I bought for just $14.99 for the set and btw, you WILL NEED them as the stock lugs are too big 21mm to be able to tighten with a socket as it won't fit in the cutout for the lug nut.

Here is the link to them on amazon:

 

Managed to get in a 60 mile trip in the car and got 56.5mpg. That is about 1/2mpg higher than my 56mpg avg with th estock rims/tires I've gotten over the last 1200 miles. Of course the speedo is now off by 2.1% with the new smaller tires, so basically it's pretty much a wash (within 1mpg after correcting for speedo).

Basically, I should be using less gas on accel due to the lighter weight wheels and tire setup. Where I'm using more is with increased rolling resistance and some increased aero inefficiency due to the rims being more offset than OEM and them poking out just a bit further into the wind. But as my numbers showed, it is basically a wash. But I feel like I definitely saw lower mpg while on the freeway portion of the trip. This tells me that if you are concerned about MPG and spend a fair amount of time on the freeway, you'l'l want to be careful about the offset you run. Another set I was looking at would have poked out another 11mm at 15x7 +35 vs 15x6.5 +40. And had I have gone with wider 205/55/15's which are nearly stock diameter at 24.1", it would have been a little odd looking up front and been even more detrimental to MPG. Especially since all the 205's I found were a couple lbs heavier than the 195's.

Stay tuned!

The wife and my son like the bronze wheels as well as myself, but my daughter likes the silver. Discount Tire hasn't shipped my second set yet with the 175 tires. I'm thinking of calling up and asking if they can switch that set to the bronze. At least that way I'll have spares if I curb one in the future!

Oh, and you can't defeat traction control without TPMS. That kinda sux but I'm not really engaging in any hijinks in the car anyway.

 

Thx Motov8r, the price was ridiculous wasn't it? I should have bought more stuff just to resell, but my wife was getting a bit annoyed with just the idea of 2 sets when the car is already brand new with new tires!

Ok, so this is kind of becoming an interactive blog. I want those on here who are on a quest for performance and efficiency to benefit from my experience/data and also be able to contribute their own thoughts/experiences.

I wanted to comment some more about the handling since I had the chance to hit the twisties yesterday. Basically, don't expect massive grip from just a rim/tire change. While it is improved, it grips nowhere near as good as my Nissan Leaf with stock suspension and 235/45/17 tires on 17x9's. The Prius has a torsion beam suspension in the rear with no rear sway bar with only a front bar. Last car I had with that setup (a cheap '96 Nissan 200SX) handled horribly with aftermarket wider rims/tires as well. I suppose I could try to find out if the front suspension has OEM adjustable camber bolts (My leaf does not, my Subaru WRX does). That is one way to increase grip on the cheap or for free. Most OEM camber bolts will give you + or - about .75 degrees of camber. Unfortunatey, you can't just add the camber without the toe being affected, so an alignment would be necessary to get it back to a zero toe setting. If the bolts aren't adustable OEM, SPC makes camber bolts that allow for + ot - 1.75 degrees and they're around $26. However, care should be taken to install them correctly. Anyway, I've done my own alignments even recently with my WRX with a measuring tape and the help of another person when I've changed/adjusted the camber bolts, but given that this is just a commuter car, there is a limit to what I'm willing to do for increased grip.

But yeah, the grip threshold has increased, but not by as much as I would have liked do to the OE suspension geometry of the car. But make no mistake, the increase in grip I have experienced with the 195/55/15's is definitely worth the money I spent, just not as much as I'd hoped for.

 

^^^Hah! Thx for the tip! I will look into that. But regardless, I can't turn down a good deal. I fig'd I could always sell the extra set if I wanted, or sell one set after I use the tires up on one of them.

Drove the car again this morn and this time without the 12 and 14yr old kids in the back that both weight about 85lbs each. Car handled better in the corners without the extra weight back there. =)

I'll go google that TRD rear sway bar right now. Thx!

 

I don't think I'll be going throught the trouble/expense of a rear sway bar. As much as I can appreciate a handling improvement, I know that several hundred spent on a sway bar is just justification for further modification. Having blown tens of thousands in the past modifying cars, I'm looking to keep this one pretty stock. My feeling is that this car in stock form is dangerous to a teenage driver as the roadholding capability is pretty severly lacking. I should not be sliding around turns at or near the speed limit. Of course the tires are to blame. I want to give my daughter more of a margin of error in grip relative to the speed limit should she mis-judge a turn and come in too fast. The 195/55/15's will go a long way in making me feel more comfortable with my kids when they're driving the car in a couple years. But for now, the 175's will be good for my wannabe hypermiling ways! And if I take a road trip through the mountains or sunday drive, I can always whip out my compressor and air gun and swap them over in a matter of minutes to suit my whims.

In other news, I switched my 2nd set coming in to bronze since the tires have yet to come in, so now both sets of wheels will be bronze.

 

Ok, UPDATE TIME!!!

Alright, so DON'T always trust manufacturer tire weights on their sites or on tire rack's site. But, the 2nd set with the 175/65/15 General Altimax RT43's are lighter by about 1.25 lbs (27lbs 0.8 oz vs. 28lbs 2.8oz) than the Hankook Ventus V2 Concept 155/55/15's.

So to review:

32 lbs 13.6 oz OEM wheel, tire & hub cap
28 lbs 2.8oz Hankook Ventus V2 concept/Konig Helium 195/55/15
27lbs 0.8oz General Altimax RT43 175/65/15

The Konig and General 175mm combo are 5.75 lbs lighter than the OEM setup vs. 4.5lbs lighter for the Konig/Hankook 195's. The General 175's are somewhere in between the OEM tires and the Hankook 195's for grip. So an improvement for sure. Just drove a few miles today so more time will be needed to get a feel for mileage benefit, but I'm happy. My garage looks like a tire shop now! Lol. But considering I used to run a tire shop out of my garage, I'm used to it. =)

Ok, here's a few pics. I got some closeups of the sidewall so you can see the difference in bulge between the 2 sizes. It is by NO MEANS a "stretched" setup running stock size on 6.5" wheels and would do fine on 15x7's too.

Ok, so for 1.25lb difference, I prob would have just stuck with the one set, but again, the price was too ridiculous to pass up and I could always throw a set on Craigslist if I needed the cash. There was another tire listed (Hankook Optimo 426) in the 175/65/15 size that showed it was .4 lbs heavier than the General (comparing weights listed on Amazon). The 14.6lbs on the General was from General's spec sheet for the tire on the website, but it was obviously incorrect and more around 15.3 lbs I'm guessing. So if the weight listed on the Hankook Optimo 426 is accurate and 15.0 lbs, it would be lighter than the General by about 4 oz after factoring in the weight of the valve stem and center cap.

If anyone has any other questions, feel free to ask. If you have any photo requests...just ask also.

1st pic bulge of 195's
2nd pic bulge of 175's
3rd pic tread and bulge wide view
4th pic 175mm rim/tire weight