205/60 R15 tires for the prius

<div class='quotetop'>QUOTE(electricity_guzzler @ May 23 2006, 03:03 PM) [snapback]259831[/snapback]</div>

I'd also like to know of firsthand experiences.

Some tires are smaller. For instance, the RPMile on the Sumitomo H4 is 862 in a 205/60-15, 874 in a 195/60-15, and 861 in a 185/65-15. Here, I'd try the 205/60-15 over the 195/60-15. Similarly, the Michelin Pilot Exalto A/S would seem to fit in a 205/60-15. As for the rim size, the Prius rims are 6" wide, which is the measured rim width for nearly all 205/60-15 tires.

In most conventional cars, I might hope that taller (lower rpm) tires would alter the effective gear ratio so that this effect might counteract the greater rolling resistance, and air friction, and unsprung weight. I doubt this is true for the Prius, with it's CVT and design for fuel efficiency. I'd like to know what fuel efficiency loss people have experienced with taller 205/60hr15 or 195/65-15 tires.

 

I am going to put on a set of Toyo Proxes TPTs, size 205/60-15 later this week. The revolutions per mile are within 1% of stock, 847 for the 205/60-15 vs 855 for the stock 185/65-15. The width is 8.2 inches vs 7.4 for stock, but I don't expect that to be a problem. I am most worried about unsprung weight, the new tires will be 19.8 lbs vs 17 for the Integritys. That extra weight will cost me on acceleration but I expect to get some back through regenerative braking.

I expect to take a 2 or 3 mpg hit but it will be worth it if the tracking and directonal stability improve. If it doesn't work out that way I'll switch back or sell the car. I already have some toe in set in as recommended by john1701a and that helped but it's still very unstable at highway speeds, especially in the wind. In any case I will post the results after I have had a chance to put a few miles on the new Proxes.

 

I put the Toyo Proxes TPT size 205/60R15 91H tires on last week and have about 600 miles on them. The change was well worth the money and this size seems to work better on the Prius than the original size. I have driven in circles with the steering at full lock in both directions and discovered no clearance problems. Tracking is greatly improved and, although I have no kind of objective test, I'm sure handling and braking are improved.

Things I could test were:

1. Speedometer error is less, compared against a good quality portable GPS unit the speedometer was close to 2 MPH fast @ 70 MPH with the original tires. Now it is about 1 MPH fast. The odometer is of course closer also but I haven't checked exactly how much yet.

2. Milage at highway speed. I run some fairly extensive (at least for me) tests for fuel milage at 70 MPH, I posted them here last October in the Prius Modifications Forum at

http://priuschat.com/index.php?showtopic=11877&hl=

I re-ran the same test with the new tires on a day when the conditions were similar, i.e. 65 degrees, no wind, etc. There were no differences, milage is still 48 to 49 MPG at 70 MPH. I was a little surprised as I expected to take a 1 or 2 MPG hit.

I don't have any real good way of checking the "around town" milage but so far I think it looks about the same as it was with the original tires.

Manufacturers data on the Toyos is at this site:

http://www.toyo.com/tires/tire_lines/passenger_car/

I'm sure a set of Michelin, Bridgestone, or other H rated all season performance tires would do as well. I think this size, 205/60R15 in an H rated tire, may be a very good choice if you want to keep the 15 inch wheels.

 

I'm glad to hear the 205s work!

I was going to upgrade to 195/60R15. The Prius shouldn't have 185s. It doesn't in Europe, Japan or Australia. They have 195's. The 4 cylinder Camry weights 373 pounds more than the Prius, but has 215 tires. 185 seems too thin for a 2,900 pound car.

It looks like there's lots of room in the wheel wells for a tire that is .8 inches wider (ie: 205 vs 185).

I don't think weight of the tire is an issue. Many people on PC put Goodyear Tripletreds on in 196/60R15. These weight 23 lbs. Nearly all said the TT had little or no impact on mileage. Some said mileage improved.

I was concerned the wider tire, especially a 205, would lower mileage. But as noted above, I'm glad to hear mpg impacts apparently will be low.

I'm thinking a good all season 205/60R15 tire plus the BT Stiffening plate will vastly improve the Prius handling in all road conditions with little impact on mileage. Has anyone tried these two?

 

<div class='quotetop'>QUOTE(nyprius @ Jun 4 2006, 10:19 PM) [snapback]265849[/snapback]</div>

Yes I have the BT Stiffening plate installed. Does it help? Well I can't say for sure because I couldn't think of a good test, just drive and see how it "feels". But I would buy it again because I think it helps.

One word of caution, when you buy new tires try to look at the revs per mile. As previously stated the original tires are 855, the 205/60s I installed are 847. I have noticed that other 205/60R15s seem to range from less than 840 up to 850 depending on the manufacturer and the particular tire. But as I said my speedometer is still a bit fast so maybe larger diameter would be just fine.

 

<div class='quotetop'>QUOTE(tumbleweed @ Jun 5 2006, 11:22 AM) [snapback]265965[/snapback]</div>

Thanks Tumbleweed! All your info is very helpful. I'll try the BT plate and I'm leaning toward the 205 over the 195 tire. The Toyo TPTs you used looks like a great tire. How much did it cost? Any sense of how it will handle in the snow? Also, I see the TPT has a 65,000 mile warranty, but the Toyo 800 Ultra has a 100,000 mile warranty. Why did you chose the TPT over the 800 Ultra?

 

<div class='quotetop'>QUOTE(nyprius @ Jun 5 2006, 12:13 PM) [snapback]266119[/snapback]</div>

No I haven't talked to anyone who has used them in the winter, they are mud and snow (M&S) rated for what it's worth. I chose the TPT because it is a performance tire which means better traction and handling, it has a softer rubber compound which I think is good. Also the H speed rating means it is constructed a little better, there is a V rated version in the 205/60R15 size also but it is 20.5 lbs vs 19.8 for the H rated tire. I also liked the tread design better than the 800 Ultra, notice the TPT has two solid bands that go around the center of the tread pattern. I think having a band (or two) such as that improves tracking, maybe a good idea with the Prius. The stiffer sidewalls of an H or V speed rating might help in that respect also.

I got them on sale for 91.98 each plus 3.50 ea for new valve stems, balancing was 14.00 ea. They gave me 15.00 each for my Integritys that had 15,000 miles on them, one of them had a flaw in it also. Total price for the whole thing came to 361.92.

For electricity_guzzler: No I didn't take any pictures, yet anyway. I started to but I really didn't think they would show much. Then I got lazy, maybe after I wash the car.

 

<div class='quotetop'>QUOTE(tumbleweed @ Jun 5 2006, 09:51 PM) [snapback]266393[/snapback]</div>

Thanks again Tumbleweed! Town Fair Tires in Framingham MA quoted me $110 per 205/60R15 TPT, but said they'd match the lowest price. Where did you get them for $92? Maybe they'll match that. Town Fair also warranties the TPT for 70,000 miles. Not bad for soft rubber!!

They also said there were better tires in the snow, something I'm interested in since I live in New England. I used to live in NY. That's why I'm nyprius... But I don't want a snow tire. I want a good all season tire that will do well in the snow compared to other all season tires.

 

I just went to Costco. The tire guy checked his tire fitment book, and said that they would only install 205/60R15 on the stock 15" rims as an alternative, and not 195/60R15. I guess it's a -0.8% error vs a +1.2% speedo error.

 

<div class='quotetop'>QUOTE(bsd43 @ Jun 6 2006, 01:02 AM) [snapback]266502[/snapback]</div>

I don't understand why Costco would say they'd install a 205/60 as an alternative but not the 195/60, when the US OEm is a 185/65. Seems it would be the other way around. Regardless of what one person at Costco says, the Prius uses 195 width tires in Europe, Japan and Australia. It's the tire the car was meant to have. 185 is suboptimal. Speedo and odo error is less than 1% with a 195/60. As Tumbleweed noted above, the Prius speedometer overreads with 185/65. The 205/60 would correct that a little since revolutions per mile are slightly lower than the OEM 185/65. The 195/60 would increase the overread a little since RPM are slightly higher.

The 195/60 will definitely fit on the Prius. As Tumbleweed said, the 205/60 fits too. The 205/60 is .8 inches wider than the 185/65. That means it will extend .4 inches from either side of the OEM 185 when mounted to the stock 15 inch rims. If you look in the wheel wells, there is plenty of room to handle that. I'll probably go with the 205/60 since looks, handling and safety will be better and mileage impacts will be minimal, as indicated by Tumbleweed above, and by many others on PC who've put wider tires on the Prius.

 

<div class='quotetop'>QUOTE(nyprius @ Jun 5 2006, 01:19 AM) [snapback]265849[/snapback]</div>

While I agree that the handling can benefit from wider tires, I noted with interest that the OEM tire size on the BMW 318i, 1992-1997, was our same 185-65-15. The 318i is heavier than our Prius. I suspect that BMW chose this tire size for all season performance and handling more than for low cost or fuel efficiency (23-31 mpg EPA). I would be absolutely delighted if my Prius would handle like a BMW 318i. This makes me suspect that the kind of tire may be more important than the size. The BMW used H rated (Continental?) grand touring tires, not goodyear integrities. Has anyone tried OEM BMW Continentals on their Prius?

I don't know what other cars used the 185-65-15 tire size besides the Prius, Corolla, BMW 318i, and pre-1993 Saab 900. I believe we can thank BMW's choice for the availability of performance tires in this size. I'm using Dunlop SP Sport A2 Plus tires. Even though the numb steering and brake feedback still make me feel that I'm driving a smaller Toyota Sienna, the Prius now drives like a small minivan on rails. (The new Bridgestone Potenza RE960 AS is also available in this size. It should provide superb performance, and was recently on sale for around $200 for a set of 4 after a $100 mail in rebate at TireRack.)

While nobody here is discussing truly low profile tires here, I wonder to what extent the trend towards low profile tires is a result of improvements in tire and suspension technology and to what extent it's merely a fashion trend at odds with optimal engineering design.

Don't get me wrong; I support using a 205-60-15 tire like a Toyo TPT on the Prius if you want better dry traction. I just think that the tire compound, design, and construction might be more important than the size in improving handling. Of course only a larger size will correct the speedometer, odometer, and mpg estimates.

I went with a 185/65-15 instead of size 195/65-hr15 Pilot Exalto AS (on sale at Costco, $332 for 4 installed) partly because I worried about grief from Toyota on any warranty repairs that they might associate with a different tire size. Does anyone know how big an issue big tires might be for Toyota?

 

<div class='quotetop'>QUOTE(theorist @ Jun 6 2006, 10:18 AM) [snapback]266611[/snapback]</div>

I agree with you that quality of tires is very important. And I'm sure a good 185/65R15 tire would work well on the Prius. That's confirmed by the many on PC who've upgraded the OEM tire using the same size.

Nevertheless, I think a wider tire will further enhance performance. You mentioned BMW from 92-97. I bet they use a wider tire now. The trend is toward the wider tire because it handles better. Better, more sporty looks are a secondary consideration. Also, nearly every other country uses a 195 on the Prius. I think it's clear the car is intended to use that size. The US just got a cheaper narrow tire in the same way we got cheaper rear brakes.

I checked with my dealer (Westboro, MA Toyota). They said the wider tire wouldn't impact the warranty at all.

 

<div class='quotetop'>QUOTE(nyprius @ Jun 6 2006, 07:35 PM) [snapback]266948[/snapback]</div>

Thank you. I think I'll use a larger tire next time and take it to Westboro if needed.

 

Just picked up two of the Toyo Proxes Tpt 205/60R15 H91 from www.edgeracing.com for $143.80 shipped. Seems like a damn good deal... B)

 

<div class='quotetop'>QUOTE(annaeus @ Jun 9 2006, 11:16 PM) [snapback]269009[/snapback]</div>

Thanks! That's a great deal!