205/60 R15 tires for the prius

[electricity_guzzler]

Has anyone tried the 205/60 R15 tire size for the prius on the stock rims?

revolutions is 846 versus 855 for the stock size. so only minor difference, less than if you put 196/65.
the rim width range is rated at 5.5" to 7.5" whereas the rim width of the stock tires is rated at 5.5" (with rim range 5-6.5), so it may actually fit at the narrowest end.

[Tideland Prius]

I'd stick with 195 since that's what they put in Europe and G Touring models in Japan. 205 might be a tad too wide.

[theorist]

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

Has anyone tried the 205/60 R15 tire size for the prius on the stock rims?

revolutions is 846 versus 855 for the stock size. so only minor difference, less than if you put 196/65.
the rim width range is rated at 5.5" to 7.5" whereas the rim width of the stock tires is rated at 5.5" (with rim range 5-6.5), so it may actually fit at the narrowest end.
[/b]

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.

[tumbleweed]

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.

[electricity_guzzler]

<div class='quotetop'>QUOTE(tumbleweed @ May 29 2006, 03:10 PM) [snapback]262410[/snapback]</div>

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.
[/b]

comfortreds are 19lbs for 205/60-15 size. i was thinking of the michelin pilot exalto because it had 850 revolutions per mile, but it is 22lbs.

hows the handling so far?

[tumbleweed]

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.

[electricity_guzzler]

[quote=tumbleweed @ Jun 4 2006, 04:24 PM) [snapback]265681[/snapback]</div>

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.
[/b]

wow. great results. do you have pictures?

[nyprius]

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?

[tumbleweed]

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

I'm glad to hear the 205s work!

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?
[/b]

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.

[nyprius]

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

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?