Tire Upgrade

[bobdavisnpf]

<div class='quotetop'>QUOTE(Dimak @ Jul 10 2007, 12:40 PM) [snapback]476298[/snapback]</div>

Would you use 205/65R15?

Thanks.
[/b]

I would use 205's but not 15's. I don't think you'll improve performance on a 15x6 inch rim with a wider tire. You may get a little better straight-line takeoff and braking, but your evasive-action and cornering stability will be worse than with a narrower tire like the 195/R15.

The basic problem is the mush factor: there is just too much ballooning out from the narrow little rim, and it has to make it all the way out to the pavement - about 5 inches of air. The wider section width means you have that much more sidewall mushing around between the wheel and the road. A narrower section width means less mush, since the sidewall takes more of a straight "path" to the outer edge of the tire.

A 16x7 or 17x7 - or even 17x7.5 - will dramatically reduce the amount of sidewall needed to get the same section width. This is where you improve evasive-action and cornering stability.

[dkit]

Thank you.

[AOV]

Thank you for all that information about upgrading the tires....my main concern is safety on the road. Planning a trip to Florida in a week, this time of year there are many torrential downpours there - their rainy season, and I have been through quite a few of them in a 1994 Toyota Corolla - it did well in it. Yet, I felt that the standard tires that are on the Prius now, probably would not do too well in that kind of rain. I am carrying precious cargo - my daughter and mom, and on the way back to New York, also my father will join us. So, safety is my number #1 concern. Will be looking into those Goodyear TT (195/60) that you recommended.

[AOV]

<div class='quotetop'>QUOTE(nyprius @ Jun 27 2006, 11:55 PM) [snapback]277872[/snapback]</div>

Thanks Theorist. Safety was my main concern too. Driving on the highway with the Integrities during a snow storm can be a real nail biter!

Based on my research, my main suggestions for someone considering replacing the Integrities are:

1. Do it, even if the Integrities aren't worn out. Replacing them with high quality all season (standard or performance) tires will vastly improve performance and safety.

2. Upgrade to the correct tire size -- 195. Like rear drum brakes, 185 width tires are sub-optimal for the Prius. A 195/60R15 works well, as would a 205/60R15. 195/55R16 might be the best if you want to change rims.
[/b]

[AOV]

<div class='quotetop'>QUOTE(nyprius @ Jun 27 2006, 11:55 PM) [snapback]277872[/snapback]</div>

Thanks Theorist. Safety was my main concern too. Driving on the highway with the Integrities during a snow storm can be a real nail biter!

Based on my research, my main suggestions for someone considering replacing the Integrities are:

1. Do it, even if the Integrities aren't worn out. Replacing them with high quality all season (standard or performance) tires will vastly improve performance and safety.

2. Upgrade to the correct tire size -- 195. Like rear drum brakes, 185 width tires are sub-optimal for the Prius. A 195/60R15 works well, as would a 205/60R15. 195/55R16 might be the best if you want to change rims.
[/b]

After reading about your research and what other had to say as well....I have decided to upgrade to the Goodyear Tripletread 195/60R15's. I am going to be on the road a lot this summer, mostly south and the torrential downpours at this time of year are practically daily (especially in the Tampa, Fl. area). I have replaced/upgraded tires all my life, but never for a Prius. Had a question about the replacement of the tires. After reading the manual....where does the tire pressure warning valves and transmitters come into play here? and does one have reset the tire pressure warning switch after its all said and done?

<div class='quotetop'>QUOTE(nyprius @ Jun 27 2006, 11:55 PM) [snapback]277872[/snapback]</div>

Thanks Theorist. Safety was my main concern too. Driving on the highway with the Integrities during a snow storm can be a real nail biter!

Based on my research, my main suggestions for someone considering replacing the Integrities are:

1. Do it, even if the Integrities aren't worn out. Replacing them with high quality all season (standard or performance) tires will vastly improve performance and safety.

2. Upgrade to the correct tire size -- 195. Like rear drum brakes, 185 width tires are sub-optimal for the Prius. A 195/60R15 works well, as would a 205/60R15. 195/55R16 might be the best if you want to change rims.
[/b]

After reading about your research and what other had to say as well....I have decided to upgrade to the Goodyear Tripletread 195/60R15's. I am going to be on the road a lot this summer, mostly south and the torrential downpours at this time of year are practically daily (especially in the Tampa, Fl. area). I have replaced/upgraded tires all my life, but never for a Prius. Had a question about the replacement of the tires. After reading the manual....where does the tire pressure warning valves and transmitters come into play here? and does one have reset the tire pressure warning switch after its all said and done?

[nyprius]

<div class='quotetop'>QUOTE(Dimak @ Jul 10 2007, 03:40 PM) [snapback]476298[/snapback]</div>

Would you use 205/65R15?

Thanks.
[/b]

I suggest 205/60R15 or 195/60R15. The 205/65R15 is too tall for the Prius. Revolutions per mile are 821 versus 855 for the OEM 185/65R15. This is a 4% difference from the OEM. It will cause speedometer under-read of roughtly 2%, making speeding tickets more likely. Plus you'll increase the risk of hitting the wheelwell. the 205/60R15 has RPM of 846. It will slightly correct inherent Prius over-read and bring you close to actual speed. 205/60 and 195/60 have the closest RPMs to the OEM tire, without changing rims.

A 205/60R15 is fine on a 6 inch rim. The 205/60 can be used with a 5.5 to 7.5 inch rim. You might be better off with a 195/60 though. This calls for a 5.5 to 7 inch rim. It would have less balloning, as another poster mentioned. However, balloning probably would not be much of an issue on the lower 205/60 (versus the 205/65). Several people on PC have put 205/60R15s on their Prius and say they work fine.

Personally, I don't think it's necessary to change the rims on the Prius. Many people have put 195 tires on the 6 x 15 inch OEM rims, including me, and not had a problem. In my case, the tire upgrade resulted in a massive improvement in performance. Most of this was probably due to the higher quality tires. But I'm sure the wider tire also played a role. The OEM size for the Australian Prius is 195/60R15. It wouldn't be specified unless it was fine for the car.

However, if you like the look of taller rims with lower profile tires, as many cars have these days, then spend the money. The taller, wider rim with lower, wider tires will hold the road better, but probably provide a rougher ride.

[Boo]

<div class='quotetop'>QUOTE(nyprius @ Jul 16 2007, 12:50 AM) [snapback]479451[/snapback]</div>

I suggest 205/60R15 or 195/60R15. The 205/65R15 is too tall for the Prius. Revolutions per mile are 821 versus 855 for the OEM 185/65R15. This is a 4% difference from the OEM. It will cause speedometer under-read of roughtly 2%, making speeding tickets more likely. Plus you'll increase the risk of hitting the wheelwell. the 205/60R15 has RPM of 846. It will slightly correct inherent Prius over-read and bring you close to actual speed. 205/60 and 195/60 have the closest RPMs to the OEM tire, without changing rims.

A 205/60R15 is fine on a 6 inch rim. The 205/60 can be used with a 5.5 to 7.5 inch rim. You might be better off with a 195/60 though. This calls for a 5.5 to 7 inch rim. It would have less balloning, as another poster mentioned. However, balloning probably would not be much of an issue on the lower 205/60 (versus the 205/65). Several people on PC have put 205/60R15s on their Prius and say they work fine.

Personally, I don't think it's necessary to change the rims on the Prius. Many people have put 195 tires on the 6 x 15 inch OEM rims, including me, and not had a problem. In my case, the tire upgrade resulted in a massive improvement in performance. Most of this was probably due to the higher quality tires. But I'm sure the wider tire also played a role. The OEM size for the Australian Prius is 195/60R15. It wouldn't be specified unless it was fine for the car.

However, if you like the look of taller rims with lower profile tires, as many cars have these days, then spend the money. The taller, wider rim with lower, wider tires will hold the road better, but probably provide a rougher ride.
[/b]

NYPrius,

I have always appreciated your thoughtful posts, especially those regarding replacement tires, and am in complete agreement with your opinion about the TTs (my own experience with the TTs is that they are the best tires I have ever had, and it's hard for me to even imagine that there's a better all around tire out there).

Because of that, when I noticed in one of the BT Tech Stiffening Plate threads that you were considering buying the plate, I was really looking forward to hearing your opinion about the plate. However, I haven't found a subsequent post by you about the plate (maybe I missed it, which would be easy to do given the length, acrimony, etc. of those threads). Did you ever buy and install the plate? If so, what's your opinion of it?

-- Boo (fellow NY Prius owner)

[nyprius]

<div class='quotetop'>QUOTE(Boo @ Jul 20 2007, 06:25 PM) [snapback]482489[/snapback]</div>

NYPrius,

I have always appreciated your thoughtful posts, especially those regarding replacement tires, and am in complete agreement with your opinion about the TTs (my own experience with the TTs is that they are the best tires I have ever had, and it's hard for me to even imagine that there's a better all around tire out there).

Because of that, when I noticed in one of the BT Tech Stiffening Plate threads that you were considering buying the plate, I was really looking forward to hearing your opinion about the plate. However, I haven't found a subsequent post by you about the plate (maybe I missed it, which would be easy to do given the length, acrimony, etc. of those threads). Did you ever buy and install the plate? If so, what's your opinion of it?

-- Boo (fellow NY Prius owner)
[/b]

Hi Boo,

Thanks for your feedback on my posts! Maybe I get a little obsessive about my car. That's why I do all the research on tires. But I think that's a healthy obsession! If it helps others, great!

I was seriously considering buying the BT stiffening plate, mainly because so many Prius owners say it greatly improves handling. I may still buy it. But I don't feel a sense of urgency the way I did with the tires. It seems highly likely that upgrading the tires will do much more to improve handling than adding the stiffening plate. But I don't know for sure since I don't have the plate.

I asked a technical question on the long BT stiffening plate thread that never got answered. So I put buying the plate on hold. I was having a hard time understanding how the plate could improve handling. Why was increasing rigidity on that particular part of the frame going to make a differnce. Also, it seemed the bolt holes for the plate were designed for smaller, weaker bolts to support a flimsier piece of metal. Would narrow weak bolts hold the stronger plate well. All the emphasis on not overtightening the bolts seemed to highlight the fact that the bolt holes we not designed for the level of stress the plate would apply. But I haven't heard of bolts snapping off once the plate is installed correctly. So maybe it's not an issue.

What I'd really like to do is test drive someone's Prius that has the plate and see if I notice a difference. The mechanic at my Toyota dealer didn't think the plate would do anything. But there are lots of owners who say it does. So I'd probably err on the side of trusting the owners. Maybe I'll buy the plate. But with the 195/60 TT's, my Prius handles very well. So I don't feel a large need to improve handling more.

All the best, Frank

[Boo]

<div class='quotetop'>QUOTE(nyprius @ Jul 20 2007, 11:31 PM) [snapback]482631[/snapback]</div>

What I'd really like to do is test drive someone's Prius that has the plate and see if I notice a difference. The mechanic at my Toyota dealer didn't think the plate would do anything. But there are lots of owners who say it does. So I'd probably err on the side of trusting the owners. Maybe I'll buy the plate. But with the 195/60 TT's, my Prius handles very well. So I don't feel a large need to improve handling more.

[/b]

Hi Frank,

I haven't put the TTs on my Prius yet, but will probably do so soon. As much as I love the TTs, I've had a hard time accepting the thought of throwing away the perfectly good (my Prius only has 1000 miles on it), albeit, bad performing Integrities.

After I install the TTs, I may install the stiffening plate. If I do, I'll be sure to let everyone know what difference, if any, I perceive the stiffening plate to make, and I will also gladly let you do a long test drive of my car (I live in Stuyvesant Town) if you want to test the plate yourself.

Anyway, time to go install the PriusChat Accessories Shop's body side moldings on my car (I already put on bumperdefender.com's 2" full-width, color-matched front and rear bumper guards, which, for their intended purposes, I like and recommend as much as the TTs).

Cheers,

Tom

[Rae Vynn]

Yesterday, while driving home from work, I hydroplaned.

I have NEVER hydroplaned before.

These OEM tires are HISTORY!!

I am getting the Michelin Hydroedges, as soon as they go on sale (next month, Costco).