Tire Upgrade

[nyprius]

I’ve benefited greatly from the experience of others on Priuschat and therefore wanted to share my experience and research related to choosing a replacement for the Prius US OEM tire (Goodyear Integrity 185/65R15). My OEM tires had 25,000 miles on them with some tread left. But I’ve had bad experiences with them. So I wanted to upgrade. I’ve gone sliding on the snow with nearly no control. The tires are very scary in heavy rain on the highway. The car gets blown around and wanders on the highway. And it feels like it doesn’t hold the road well on turns. The Integrity is an OK basic tire. But as many others on PC have said, upgrading it will lead to vast improvements in handling.

When I looked on PC for tire recommendations, many tires were suggested, but three seemed to be recommended the most – Michelin Hydroedge (HE), Goodyear Comfortred (CT) and Goodyear Tripletred (TT). The TT was rated the best all season passenger car tire by Consumer Reports and Tirerack. I didn’t fully trust the opinions given on Tirerack and other self-entered tire opinion sites, such as epinions and 1010tires. On these sites, owners give opinions with little frame of reference other than the previous tires on the same car. These would have been worn down, so almost any new tire would feel better. More importantly, marketing people for the tire companies can enter good ratings on the sites. I have no proof that this occurred, but if you read the opinions given on the above sites, you’ll see many were almost certainly written by tire marketing people, since no one would talk about tires this way in the real world.

While the tests of Consumer Reports aren’t perfect, at least they’re unbiased (I hope). Tires are compared to peers on the same tests and cars. After looking at many tires, I preferred the TT. Of course, this is a personal opinion. The CT and HE are both great tires. As noted by others, they work well on the Prius. But given all the tests and opinions (even assuming many were from Goodyear), I was leaning toward the TT.

The problem was it didn’t come in the OEM size. I originally had a strong preference for sticking with the OEM size. However, as I researched it, I saw that Europe, Australia and Japan (where the Prius is designed and built) use a 195 width tire. The Prius is designed for a 195, not a 185 tire. I assume the US got a cheaper tire to keep costs down, in the same way we got rear drum brakes, while most other places get rear disk brakes. Alternatively, knowing the US appetite for more and better things, the US Prius may have been intentionally dumbed down (ie: narrow tires, rear drum brakes, front seats with no height adjustment, etc) so future Prius’s could be easily spruced up, thus prompting turnover among Prius owners who want the best.

Further evidence that the Prius is designed for 195 tires is the fact that the 2007 Prius will be offered with 195 tires in some option packages. (It is extremely unlikely that Toyota makes smaller wheel wells for the 185 tires. All Prius wheel wells probably are the same around the world.) Following an 04-06 US Prius on the highway, it looks like the car has bicycle tires. If you review the specs, very few cars of the Prius’s size and weight use 185 tires. 185’s are usually used on smaller cars. Given all this, I decided there’s no way I’m putting undersized 185 tires on the car again.

The problem with the 195 is tire height. If I wanted to change rims and go with a 195/55R16 (the tire used in Japan and Europe) I could get nearly the same revolutions per mile as the US OEM tire (855), which means speedometer/odometer readings and ground clearance would remain the same. But I didn’t think it was necessary to change the rims. 6” wide rims, such as those on the Prius, can handle up to a 225 width tire.

In the 195, I looked at the 195/60R15 and the 195/65R15. The 195/60 has 863 RPM (.9% higher than the US OEM). The 195/65 has 836 RPM (2.2% lower than US OEM). According to others on PC, the Prius speedometer over-reads by 1-2 mph (ie: it says you’re doing 60 when you’re really doing 58 or 59 mph). The 195/60 has less than half the distortion of the 195/65. It would increase the over-read by less than 1%, whereas the 195/65 would reduce over-read by more than 2%, possibly resulting in under-read (a more risky condition). Personally, I don’t mind a little over-read. It helps to minimize speeding tickets. The radius of the 195/60 is .325 cm less than the 185/65 (about one eighth of an inch). So ground clearance won’t be affected significantly. (The 195/60 tire is .65 cm shorter than the 185/65, but the car would only be .325 cm lower.)

I also considered a 205 width tire. There appears to be plenty of room for this on the Prius. Others have reported that the 205 works fine on the Prius. If you turn the wheel all the way to one side and run your hand around the interior sides of both front tires (US OEM 185), you’ll see there’s more than an inch between the tire and all points in the wheel well. A 205 is .3” wider than the true Prius OEM tire (195). This means it would extend .15” beyond the designed tire width toward the interior side, which is no problem. A 215 would probably work too. I considered the 205/60 because it has 846 RPM, (1% lower than OEM). This would partially correct speedometer over-read and give about .1” more ground clearance than the 185/65 US OEM tire.

I probably would have gone with the 205, but I noticed the tread width on the 195/60 TT and 205/60 TT are the same (6.4”). Therefore the wider tire would not give me wider contact at the road surface. I decided to go with the 195/60R15 TT because I felt the slightly lower tire would give me better cornering and less wind resistance. I felt the 1/8” less ground clearance (compared to the US OEM) and slightly higher speedometer over-read were not significant.

Also, while it seemed certain the 205 would work in the Prius wheel wells, I felt a little uncomfortable going beyond the “real” OEM width (195). Fortunately, the 195/60 TT gave me the best of both worlds. I got the wider tread without having to go with the wider tire. In terms of road contact, the 6.4” tread width of the 195/60 TT compares to 5.7” for the 185/65 CT. The HE tread width is not listed but is probably about the same as the CT. This indicates the TT will corner better with little, if any, mpg loss, as reported by others on PC who are using the 195/60 TT.

I put the 195/60 TT’s on a week ago. On dry pavement, the car sticks to the road like glue. The car seemed to be as stable in sharp turns as when going straight. I just got back from a 400 mile trip mostly in the pouring rain in Massachusetts and Vermont. Much was on route 2 in MA. A narrow 4 and 2 lane fast moving highway with lots of construction. On the US OEM tires, I would have felt like I had no margin of safety when driving at 65 in the rain on this road. I often gave up on trying to pass someone with the old tires since the car felt too unstable. With the new tires, the very wet road usually felt like a dry road. I felt I had a wide margin of safety – that I wasn’t anywhere near losing control. The car felt stable going through deep puddles too. No hydroplaning.

It was the same on the 2 lane Vermont 50 mph highways. I was cruising at 60-65 on windy country roads often in heavy rain. The car again felt very stable and safe. I also got over 50 mpg for the first time ever in my car. In the summer, I get 45-47 on the type of drive I did this weekend. This time I got 52 mpg. I was surprised. Part of the reason might be the .9% over-read on the speedometer/odometer due to the 195/60 tires (ie: when the odo says the car went 100 miles, it only went about 99).

Bottom line: The US OEM tire is poor quality and not the right size for the Prius. Putting good 195/60R15 or 205/60R15 tires on the car is an easy and relatively inexpensive way to greatly improve the performance and safety of the Prius, with little or no mpg loss. The car looks a lot better with the 195/60 TT too. The 195/60 is .4” wider than the 185/65. This is noticeable. It makes the car look more stable and solid. This is the way the car was designed to look.

[ncc1701mda]

What tire pressures are you running and how does that compare with what you ran in the stock tires? Also, have you checked the speedo reading using the distance over time method on an interstate to see how far off it is?

Mike

[nyprius]

<div class='quotetop'>QUOTE(ncc1701mda @ Jun 26 2006, 01:31 PM) [snapback]276876[/snapback]</div>

What tire pressures are you running and how does that compare with what you ran in the stock tires? Also, have you checked the speedo reading using the distance over time method on an interstate to see how far off it is?

Mike
[/b]

Mike, I'm running the same tire pressure as on the old tires: 42/40. I haven't used the method you mentioned to see how much the speedo is off. I'm not too worried about it because I know the differnce in speedo reading between the old and new tires will be less than 1%, based on tire revolutions per mile.

Frank

[Syclone]

<div class='quotetop'>QUOTE(nyprius @ Jun 26 2006, 03:28 PM) [snapback]276944[/snapback]</div>

Mike, I'm running the same tire pressure as on the old tires: 42/40. I haven't used the method you mentioned to see how much the speedo is off. I'm not too worried about it because I know the differnce in speedo reading between the old and new tires will be less than 1%, based on tire revolutions per mile.

Frank
[/b]

Your data on the tire change look very impressive. I agree with the comment about the Prius looking like it had bicycle tires when viewed from the rear. (Of course I hate to think what I look like when viewed from the rear). I only have 1500 miles on my car, so I expect it will be a while before I make a tire change. But I probably buy 195's or 205's when I do make the change.

Speaking of MPH errors. I use a Garmin IQue 3600 GPS receiver in my car and I've noticed that the difference in MPH between the Prius speedo and the Garmin speedo is usually less than 1 MPH. The difference varies because the Prius displays whole digits only, while the Garmin displays in 10ths. The comparison should be valid, because the Garmin unit updates once per second.


Sy Cohen

[silentak1]

Thank you for the info. I'm actually already at 32,000 miles ('05) and two of my tires show heavy usage (despite 10,000 rotations and alignment).

Speedometer "misreadings" was a concern of mine, but the 195/60s seem to be a good solution. Now it's time for me to pick some good all season tires... onto another thread...

[nyprius]

<div class='quotetop'>QUOTE(syclone @ Jun 26 2006, 03:56 PM) [snapback]276958[/snapback]</div>

Your data on the tire change look very impressive. I agree with the comment about the Prius looking like it had bicycle tires when viewed from the rear. (Of course I hate to think what I look like when viewed from the rear). I only have 1500 miles on my car, so I expect it will be a while before I make a tire change. But I probably buy 195's or 205's when I do make the change.

Speaking of MPH errors. I use a Garmin IQue 3600 GPS receiver in my car and I've noticed that the difference in MPH between the Prius speedo and the Garmin speedo is usually less than 1 MPH. The difference varies because the Prius displays whole digits only, while the Garmin displays in 10ths. The comparison should be valid, because the Garmin unit updates once per second.
Sy Cohen
[/b]

Thanks Sy,

I'm glad to hear the speedo isn't as far off as I thought!

Many people on PC put new tires on before the Integrities wore out, some as soon as they got the car. There was no way I was going through another winter with the Integrities, though I technically had enough tread to do so. I figured I'd get the new tires now and break them in before winter. Also, I figured the car would be much more fun and safe and that I'd feel better having high quality right sized tires rather than low quality wrong sized.

Frank

<div class='quotetop'>QUOTE(silentak1 @ Jun 26 2006, 09:25 PM) [snapback]277111[/snapback]</div>

Thank you for the info. I'm actually already at 32,000 miles ('05) and two of my tires show heavy usage (despite 10,000 rotations and alignment).

Speedometer "misreadings" was a concern of mine, but the 195/60s seem to be a good solution. Now it's time for me to pick some good all season tires... onto another thread...
[/b]

Good luck! The 195/60 TT's are great, but I don't want to sound like I work for Goodyear!

[theorist]

I'm a little confused as to why so many priuschatters seem to only be considering tires marketed as standard all season tires like the Goodyear Assurance Tripletreds or Comfortreds or the Michelin X or Hydroedge. I agree that they are the best among a crowd of otherwise lousy tires.

What I don't understand is why I don't hear more people comparing any of these with all season performance or touring tires like Michelin Pilot Exalto A/S, Dunlop SP Sport A2 Plus, Yokohama H4S, Continental ContiProContact, Bridgestone RE-960as, Toyo TPT, Falken ZE-512, or Sumitomo H4?

Are people only considering the tires in Consumer Reports latest tire test, which restricted itself to standard all season market segment, and so not considering any touring or performance tires? Are they only looking at tires with the longest treadwear?

[NuShrike]

<div class='quotetop'>QUOTE(theorist @ Jun 26 2006, 09:46 PM) [snapback]277218[/snapback]</div>

I'm a little confused as to why so many priuschatters seem to only be considering tires marketed as standard all season tires like the Goodyear Assurance Tripletreds or Comfortreds or the Michelin X or Hydroedge.
[...]
What I don't understand is why I don't hear more people comparing any of these with all season performance or touring tires like Michelin Pilot Exalto A/S, Dunlop SP Sport A2 Plus, Yokohama H4S, Continental ContiProContact, Bridgestone RE-960as, Toyo TPT, Falken ZE-512, or Sumitomo H4?[/b]

How about some BF Goodrich T/As also?

My take is back, back when the early adopters researched tires and picked what they thought were the best, this wisdom and bias was then passed on...

These drivers were:
1) fairly normal drivers so "performance" tires weren't a draw
2) Tirerack's "survey" results were used to rate the tires found, and the standard tires tended to rate higher than the performance tires (even though the "survey" results do not translate across classes)
3) the picked tires' improvement in grip, noise and comfort over OEM were "good enough", and gets established as a long history of best practices and recommendations in many Priuschat threads
4) maybe Consumer reports had some effect

For #2, IMO the numbers do not translate across classes because they are subjective numbers to begin with, and conservative drivers do not know (generally) what real performance tires should feel like/perform, and maybe vice versa. The only way to tell is to compare tires head-to-head on the skid track, and there's very little demand/need for that with the usual temperate profile of a Prius driver.

It can't be for MPG because some of the "usual" tires are a bit heavier than OEM versus the performance tires, and some more expensive even.

Maybe this helps?

[nyprius]

<div class='quotetop'>QUOTE(theorist @ Jun 27 2006, 12:46 AM) [snapback]277218[/snapback]</div>

I'm a little confused as to why so many priuschatters seem to only be considering tires marketed as standard all season tires like the Goodyear Assurance Tripletreds or Comfortreds or the Michelin X or Hydroedge. I agree that they are the best among a crowd of otherwise lousy tires.

What I don't understand is why I don't hear more people comparing any of these with all season performance or touring tires like Michelin Pilot Exalto A/S, Dunlop SP Sport A2 Plus, Yokohama H4S, Continental ContiProContact, Bridgestone RE-960as, Toyo TPT, Falken ZE-512, or Sumitomo H4?

Are people only considering the tires in Consumer Reports latest tire test, which restricted itself to standard all season market segment, and so not considering any touring or performance tires? Are they only looking at tires with the longest treadwear?
[/b]

Actually, I did look very closely at all the tires you mentioned, plus the BF Goodrich T/As, plus many others. I spent a lot of time reading reviews, going to tire stores looking at tires, and speaking with tire experts. I seriously considered the Toyo TPTs for example. But many reviews said these tires are terrible in the snow. If you look at the tread, you can see why that's true. I choose the TT not because of old wisdom said by others on PC. But because after extensive research of all classes of all season tires (all season, performance all season, high performance all season, ultra high performance all season, grand touring all season, standard touring all season) I thought the TT would be the best all around tire.

Based on my experience so far, the TT holds the road perfectly. While I'm not a professional race car driver, I've driven many sports cars so I generally know what good performance means. Perhaps high performance tires would hold the road slightly better. But I don't drive the Prius like a sports car. I want it to work well under all conditions, especially rain and snow, which we get a lot of in New England. Based on feedback from many tire experts I didn't think any of the performance tires mentioned above or elsewhere, except for the Nokian WR, would do better than the TT in the rain and snow. (While the Nokian WR is better than the TT on snow, it's not as good on noise, mileage and dry performance.)

The all season tires are designed to balance many factors -- mileage, noise, comfort, as well as dry, wet and snow performance. Performance tires obviously lean toward performance, often focused on dry pavement at speeds over 100 mph. Many sacrifices are usually made when going for the performance tire. Performance tires usually have no or a low mileage warrenty. I suspect for the average Prius driver, the best balance of all factors is preferred. I haven't seen a lot of people driving Prius's like sports cars, dodging in and out of traffic, racing, etc. The Prius is intended to be a passenger car, not a sports car.

Obviously, I haven't tried all these tires on my car. Even if I did, I probably couldn't tell the subtle differences in performance. But the Prius is not a race car. So it probably doesn't matter. The extra edge in high speed turns is irrelevant for most Prius drivers I suspect. The far more relevant factor is safety under all road conditions. Based on all the research I've done, which is a lot, I felt the TT was the best tire for the Prius out of ALL tire classes.

But again, this is just one person's opinion. Perhaps there is a better all around tire for the Prius. However, I doubt it would be substantially better than the TT for most Prius drivers. One thing I do know for sure, the TT is hugely better than the Integrity!

[TomKahn]

I upgraded to using 205/60 R15 Falken Ziex Ze 512 and I am very happy with them at $43 each.

You can see them at: http://www.edgeracing.com/2005/Toyota/Prius/tires/15/


Falken Ziex Ze 512
205/60R15 20.1Lbs. 420 Treadwear UHPAS H Rated The Falken Ziex 512 received first place in a comparison test done by a leading consumer magazine. One of our best sellers due to its high treadwear More...
Stock Status: Usually Ships Within 24 Hours.

Great in the rain, Better in the dry, Good in the snow. This mod did more for better handling then the bt brace or any other mod. I recommend highly.

Tommy Kahn