Number6

A few months ago I bought a 2009 RX 350. It came with the original Michelin tires. But I also got Cooper Discoverer winter tires (used) mounted on rims. Both Michelin and Cooper still have more than half the tread left.

Using the Michelin on highways with the cruise control set at 65 mph, I averaged 28mpg. Last week I went for my service appt. at the dealer and had the vehicle switched to winter wheels. I drove 500 miles this past weekend at the same speed of 65mph and my mpg dropped by 18%.

So I decided to switch the Lexus back to the Michelin and drove 200 miles at the same 65 mph and my mpg was back to 28 mpg.

The methodology I used to measure the distance travelled was resetting the odometer and for gasoline, I filled up the tank right up to the gas cap. And yes, it is a royal PITA to do that.

RX330inFL

Welcome to Club Lexus.

There are a number of threads here discussing the topic of tires and MPG. Use the search tools to look around the forum(s) as needed.

It is not abnormal to see such a difference between brands of tires. Each has different tread patterns and tire compounds that affect the rolling resistance. Will assume each set of tires is set to the same air pressures and each are the same tire size.

The Cooper Discoverer CTS, the only Discoverer tire I could find in a size to fit one of the two stock tire sizes for the RX, is not really a winter tire. Just your regular all-season tire.

http://us.coopertire.com/Tires/Sport...VERER-CTS.aspx

The OEM Michelin tire is actually pretty good in light snow conditions. So, you are not losing anything there. If you have an AWD RX you should be OK.

Q. Are both sets of tires of the same measurements? 225/65R17?

Finally, be careful filling your tank in that manner. You run the risk of ruining your evaporator canister amongst other issues. http://www.epa.gov/donttopoff/

Number6

The Cooper are 235/65R17, while the Michelin are 22/65R17.

Such a dramatic loss in mpg is unacceptable, but how many have taken the time to carefully and accurately measure their mpg? I am dismayed by such performance and do not intend to use them. It cost me $120 in fuel for my 500 miles. If I had the Michelin, it would have cost me $100.

For identification purposes:

https://www.tiresavings.com/tireShop...scoverer+M%2BS

P.S. I know filling up the tank right up to the gas cap doesn't make a lot of sense, but I don't have a choice when I wish to have exact and precise measurements of my mpg. Btw, between the first time the gas pump stops up until you reach fuel up to your gas cap, there is about 1.3 gallon.

hypervish

Also, keep in mind that gas stations are now switching to winter gas. So, that might account for the mpg loss.

Number6

I doubt it very much. Moreover, I filled up at the same gas station once back from my trip and when I measured my mpg this summer as well as after I reinstalled the Michelin and drove 200 miles this past week. It is a lot of trouble and more than $50 wasted on gas, but at least I know where I stand.

P.S. I basically always fill up at the same gas station, as much as possible.

RX330inFL

Well, those are truly "snow" tires:

http://us.coopertire.com/Tires/Sport...VERER-M-S.aspx

Still, you cannot really compare the Michelin tire to these. Snow tires are designed for maximum traction and surface adhesion. Am going to guess that had you left those tires on for the rest of the winter season they would have been used up a good amount of the tread depth by the time you took them off. Thus, be definition they suck when it comes to rolling resistance and MPG.

While minimal to this discussion, the difference in tire size also had an effect on your MPG calculation as well as your odometer since the Cooper is a taller tire (225/65-17 vs. 235/65-17) by half an inch or more.

Number6

The small difference in size is in the end meaningless as there are other factors to take into account, like for example, the wind speed. So possibly one factor cancel the other and most likely has a less than 10% impact (1.8%) on my 18% drop in mpg.

In the end, as far as I am concerned, it is unnaceptable. I guess it might be because it is an SUV, because I have never experienced such a dramatic loss in mpg when installing winter tires in all my sedans.

RX330inFL

As I said, "minimal to this discussion[.]"

If you live in the rural sections of NY where winter tires are truly required for the deep snows off the lakes you will perhaps want to look at one of the Bridgestone Blizzak models. Hard to go wrong with those.

http://www.tirerack.com/tires/TireSe...ting=S&tab=All

I have driven in six inches of light snow in PA on a used set of OEM Michelins as well as my current Bridgestone Alenzas in a FWD RX and have not had any problems. Not even on the back roads I drive which are rarely plowed in a timely manner.

Number6

Thanks for the suggestion. Btw, the Consumer Reports issue of November 2011 evaluated SUV tires, so I'll have a look too. For now, I intend to just use the Michelin and abstain from driving it in heavy snow. Shouldn't be too hard with the weather we are having...

RX330inFL

They list the Michelin X-Ice XI 2 as their top choice according to the online edition. Seems to have good ratings at Tire Rack as well, though lower rated in snow when compared to others such as the Pirelli Scorpion Ice & Snow and the Blizzaks. Never heard of the Nokian brand Consumer Reports also discussed.

Only light snow so far here in the Poconos. Not sure what the season will hold. Luckily, will be heading back south after hunting season.

stunt66

Something doesn't sound right, if theyre that close in size there's no way you can lose 18%. I run a skinny winter on my truck and in the summer i use a wider and heavier a/t tire and there is minimal loss in mpg. I've literally watched every tank since new and the only time i see a big loss is in winter but thats because i use the heavenly remote starter lol

Number6

It might not sound right, but there is no mistake in my methodology. They might perform very well in the snow (I don't know), but they are crap for mpg. That's all.

mandyfig

Green tires nowadays will offer low rolling resistance. This is component that Auto makers play around with.

It is all about weight. And it is all about MPG.

Some of you know what the answer is to this question:

Why do auto makers do not include the mats with the car? And you have to pay for or negotiate with the dealer for it?