Tire Upgrade

Aye, I've often thought about this. Perhaps it's market-led. Prius here only comes in relatively high-spec packages, even the basic model has a lot of extras. Most cars now have disc brakes all round by the way, only cheap ones don't.

On the subject of handling, if the car feels like it's wandering, unstable, harsh etc, let some air out of the damn tyres! 42/40 psi, when I tried it, caused all those problems and more!

Why would Toyota spec 35/33 without a good reason?

 

What's the best rim size for a Sumitomo 205/60 HR15? TireRack's site recommends a 6" rim, but on their rims page the 15" x 6" rims are all linked to 185's and 195's. Would 6.5" or 7" be a better rim choice for this tire? Sumitomo's "measured rim width" is 6" but its range is 5.5" to 8".

After seeing comments here and at TireRack re: Sumitomo HTR200 wet-traction performance, it looks like a fine year-round tire for Puget Sound. (We get, like, 4" of snow per decade. When it reaches 0.1", we all stay home and watch SUV's slide sideways on the news.) The low rolling resistance is a huge plus, as is the more-accurate speedo reading.

Thanks,
Bob

 

<div class='quotetop'>QUOTE(bobdavisnpf @ Aug 14 2006, 01:49 PM) [snapback]303074[/snapback]</div>

I'd go with a 6" wide rim, the measured rim width as you point out. The original rims on your 2006 Prius are 6" wide and should fit the Sumitomo HTR 200 size 205/60HR15 beautifully. Let us know how you like the Sumitomo HTR 200 tires!

 

<div class='quotetop'>QUOTE(Green Speed @ Aug 10 2006, 12:18 AM) [snapback]300628[/snapback]</div>

Sweet ride is right. My wife's Prius looks just fine parked next to my Corvette. They look like a team of technological marvels. With these wheels and our tinted windows, this car looks 100% better.

The sensors moved just fine, apparently. Contrary to the tire calibration formula on the Discount Tire site, these tires are a tad too small. According to the GPS program on our laptop, when the speedometer says 65, we're only going 63. I expected better. I suppose if I do it again, I'll get the 50 series instead of the 45.

We got 43 MPG on the trip, running at 70+ MPH most of the time. That's not unreasonable, but I'm not sure how to figure in the speedometer change. These were also running 40/38 pounds of pressure. These tires are so smooth and forgiving, that I've upped them to 42/40 and they're still great. Quiet, too. I just love the way this car drives now.

We don't have the Nav system. Anyone know how to recalibrate the speedometer?

Oh, I almost forgot. I paid about $1250 for the wheels, tires, mounting and the mounting of my Michelin snow tires on the OEM rims.

 

<div class='quotetop'>QUOTE(mongo @ Aug 20 2006, 10:53 PM) [snapback]306510[/snapback]</div>

People with 185/65-15 size tires are also finding that their speedometers read 1 to 2 miles too fast compared to the mile marker or GPS readings. And this is with new tires. As the tires wear from 10/32" to 2/32", the tire diameter will decrease and the speedometer readings will increase by 2% more.

Your tires revolve 856 times per mile, according to BFGoodrich and the TireRack. The OEM Integrity does 855 revolutions per mile according to Goodyear and TireRack. It makes sense that you are getting the same speedometer over-read as OEM tire users. This error will also another 1 mpg worse as the tread wears.

I believe that with the built in navigation, the speedometer calibration does not change the speedometer or odometer display only the navigation system's use of the speedometer for dead reckoning in the absence of a good GPS signal.

I like your idea of using a tire with a slightly larger diameter. It's worked for me. I'm using 195/65HR15 ContiProContact tires. My speedometer and odometer read about 1% (less than 1 mph) too slow. As the tires wear, I expect the speedometer to read about 1% too fast. The 195-65-15 tires correct the speedometer error and don't scrub or rub in anyway. I wouldn't know if a 205/50-17 or 215/45-17 tire might scrub wheel well or suspension parts.

 

Great thread, everyone!

Since my car is brand new and since I have the Integrity tires...I'm going to see them through this winter at least, but after reading everything, my next tires will probably be GY TT 195/60...I have steep hills I drive all the time...and rain, ice and snow...so will see how I do this winter.

 

<div class='quotetop'>QUOTE(theorist @ Aug 21 2006, 01:00 AM) [snapback]306566[/snapback]</div>

That's interesting. We never checked the GPS-measured speed with the original tires. I just assumed it was correct from the factory. What was I thinking?! So, we can compare our current mileage to that with the previous tires without correcting for tire size. Cool.

Terri, the tires I just bought are superb summer dry/wet tires, but worthless on snow. We have a set of Michelin X-Ice tires for that purpose. I believe in using equipment designed specifically for the road conditions rather than using a tire that gives reasonable performace all year round. "Real" snow tires make a huge difference. Our Prius in the winter is like a tractor. I haven't run into snow that can stop us yet.

 

<div class='quotetop'>QUOTE(mongo @ Aug 21 2006, 11:32 PM) [snapback]307312[/snapback]</div>

Thanks, Mongo....I agree. In my case, since I was always pressed for time, I kept my Blizzaks on year round...and I know they wore out faster, but I would rotate them and then just get new ones.

With the Michelin X-Ice....are the wider than the Integrity...the OEM Integrity looks like a toy tire.


Did you have to change anything to put them on? Rims? Sensors? Isee that you said you paid $1250 for whole thing...wheels, tires...how are rims different from wheels? Sorry...I'm ignorant about some of this.
You could use the OEM rims but needed new wheels?

I must get a photo posted of our hill outside our house...Oh...I do have one!! in the snow yet...will attach here:


Actually, this photo was taken from my front door so it is of the down-going hills in front of the house...my driveway is on the other side and that hill is short and VERY steep.

The snow plow got stuck in the ditch on our street one year....we have buses, and cars and SUVs and plows that think they can get up the hills in an active snow and end up in the side ditch and need a tow.

 

Never be afraid to ask, Terri. That's why we're here. We want to help one another.

Rims = wheels = the metal part

Tires are the rubber part only

I paid $1250 for 4 Enkei 5+ 17X7 rims and the BF Goodrich g-Force Sport tires (205/45X17) that went on those rims. I already owned the Michelin X-Ice tires from last year (185/65X15) and those were mounted on my OEM rims. I think I paid around $90 each for the snow tires. They moved the sensors from the OEM rims to the new rims. They'll have to move them back in the winter unless I buy more sensors.

I bought the new tires, because I thought the OEM tires were a joke. They suck in every condition IMHO. I may have sacrificed some mileage performance because the new rims/tires are a few pounds heavier and about an inch wider. On the other hand, they feel great! The car rides smoother, doesn't wander on the highway and corners much, much better. These are excellent tires. The fact that the new setup looks fantastic is also a plus.

I've always heard that wider is not necessarily better when it comes to snow tires, but I think that depends on the type of snow. Wider tires don't "bite" as hard as narrow tires. In any case, looking at your lovely winter scene, you definitely need SNOW tires. Especially if your plows are getting stuck. Yikes.


Good luck!

 

Thanks, mongo!!

I thought wheels =rims.....thanks also for the additional info.

I will print and save for when I replace these tires. I'm a bit hesitant about even keeping my OEMs for the year...but...will.

terri

Also...when I was working AND full-time caregiving...it got so changing tires from summer to winter was a real pain....that's why I left my Blizzaks on year round...they were GREAT on my hills in the snow...not even bad on ice....

mongo..your Michelin "snows" were 185s...that's narrow, isn't it, like the OEMs?

Also...sensors? Where are they and what is the purpose? I thought it was something to do with the rotation of the wheel...related to distance....Now I have no clue.

Thanks for helping so much! I love these forums. I have learned so much already about my Prius....I hate having something so beautiful and high-tech as the Prius...and not knowing what things mean...the MFD was what grabbed me!!

I am so grateful for this thread...I am stopping by my mechanic's shop tomorrow....I do so little driving...but getting out of my neighborhood onto fewer hills can be a real necessity for me at times....so I am definitely getting some snows before winter...

My Integrities slipped already several times when I turned around to back down our hill into the driveway...when I had to pull forward slightly to get into position, it was in a steep uphill position and the road was a little wet and the tires slipped as though there were ice on the road...or as if we had packed wet leaves in the Fall.

I just took a quick look at comsumerreports.org 11/05 recommendations for snows...

Michelin X-Ice was the TOP rating for severe winter performance.....
although some issues with braking with ABS...

The Vikings were second, but fgor moderate winter conditions. (We can go a whole winter with "moderate" conditons, but one winter we had 18 major snow storms....this neighborhood is a killer)

Goodyear Ultra Grip were 3rd...

Bridgestone Blizzaks WS-50 were 4th (I have always used these and they have been fantastic on my hills)

So...now I will ask around and hopefully, more people will post here...but right now, I would go with Michelin X-Ice or Blizzaks....

I can keep my Integrities for spring/summer...they are fine for my use at these times of the year and this will give my winters a break.





terri

 

Yes, my snows are exactly the same size as the OEM tires. But they look better. And they work like crazy. I'm sure I used Consumer Reports as one of my guides. When you're looking for tires, here are a couple of other sites to check for information and great reviews:
www.tirerack.com
www.1010tires.com

The speed sensors are in the metal valve stems. Who knew? I just learned this myself recently.

We kept our OEM Integrity tires for 16,000 miles and even used them through the first winter. Not much fun.

We buy all our tires (and wheels) from our local Discount Tire store. They rotate the tires for free and swap them twice a year for practically nothing. All it costs me is a couple of hours, two Saturday mornings a year.

 

Thanks, mongo...I wrote down those sites.

So there is a speed sensor...and a TPMS...Tire Pressure Monitoring Sensor? The speed sensor affects the mph, I would assume?

I used to use some discount tire places...but seemed to have problems with the tires...more flats...maybe my imagination. Now I have my mechanic buy and put on...maybe this first set I will have Toyota do...
I am bringing all my info to Toyota service today when I go to have the new rear bumper (it was defective) put on.

terri

 

We have a 2004 Prius. They don't have tire pressure sensors.

I hope you have a good Toyota service center. I tend to use dealerships strictly for warranty work. I go to tire stores for tires. For everything else, we've got an excellent (very honest) mechanic that we've used for many years. Oh, and I do as much as I can myself. When we bought our car, I purchased the complete set of service manuals.

 

After reading tire reports for several months and wanting to replace the OEM tires I took the plunge. Hydroedge in 195-65-15 . No where near the noise as the Goodyears, Better ride and they just feel better on wet road. Now I will see about the mileage hit after the break in. Running 40lbs front 38 rear and the ride is not harsh so i'm happy

 

Hiya ralph,
What is your actualy mileage hit? 5 mpg like the rest?

 

The service rep at Toyota yesterday said he buys all his tires from tirerack.com, which was mentioned here as well.....

So...the consensus here, is I will go this winter with my Integrities...I really don't even go out in snow anymore. I am retired and can choose not to go in the snow....I should be able to climb our hill once it's plowed and sanded.....and if I need to get hubby to hospital in a snow, I would call the EMTs anyhow!

So...I will see...if I have a problem...I will buy the Michelin-X-Ice and have them installed at Toyota...I do have the TPSM...so don't know what they do with that?

This has been a very informative thread!

terri

 

<div class='quotetop'>QUOTE(terri @ Aug 24 2006, 07:14 AM) [snapback]308725[/snapback]</div>

I believe (though I haven't swapped out my tires yet) all you have to do is to get the person swapping out the tires (assuming you keep the same wheels/rims) to remove the sensors from the existing tires and place/fix them into your new ones. I'm getting my new wheel/tire combo today.

It's my understanding that the sensors are tires specific not wheel/rim specific. And anyways with the new tires on your wheels i believe each unit (tire & wheel combined) has to go through 'rebalancing'.

 

<div class='quotetop'>QUOTE(Green Speed @ Aug 24 2006, 12:12 PM) [snapback]308804[/snapback]</div>

The service person mentioned that each unit has to go through rebalancing...at any rate, I would Have Toyota put on the tires anyhow...

 

Only 200 miles so far looks like about 2-3 mpg so far. I will let you know after about 1k and see what happens. (lets see 1k miles that should be about 2 weeks.)

 

<div class='quotetop'>QUOTE(Green Speed @ Aug 24 2006, 12:12 PM) [snapback]308804[/snapback]</div>

Actually the TPMS (Tire Pressure Monitoring System) sensor-transmitters are attached to the rim. I believe they don't touch the tire. Unfortunately I didn't take any photos of the ones I saw. DocVijay said he'd take some photos of the ones he bought. Attached to the metal valve stem is a piece of black plastic with codes written on it. The plastic shell contains a lithium battery, pressure sensor, and wireless transmitter. The plastic shell is VERY approximately 1cm x 2cm x 4cm. It lies close against the rim, behind and held in place by the metal valve stem.

Replacing tires on a set of OEM rims with TPMS should not involve the TPMS except that you don't need or want new rubber valve stems. The machines that dismount old tires often 'scrape' the inside of the wheel to cut off the old valve stems at the same time. If the tech replacing the tires isn't alert and does this with TPMS equipped [rims] the dismounting machine can break a TPMS sensor/transmitter. Remind the shop that your 2006 or later Prius has TPMS and to be careful to not damage the sensors (transmitters).

<div class='quotetop'>QUOTE(ralph b @ Aug 24 2006, 07:05 PM) [snapback]309041[/snapback]</div>

About 1-2 mpg of that difference is not real, only measured. Your new and larger 195/65-15 tires revolve about 2% fewer times per mile than a new OEM 185/65-15 size tire and 4% fewer times than a fully worn OEM size tire. If you replace fully worn (down to the 2/32" tread wear indicator bars) OEM tires and find that your measured mileage fell 2mpg, your true mileage may have not changed. The car just thinks its not traveling as far, since it can only measure wheel revolutions, not really distance travelled.