replacing OEM tires with a plus size tire

There are many threads which discuss this.

My take of what people said in those threads
is that you take a very small mileage hit when
you increase the tire size, but you gain a lot
in additional handling and other tire performance
factors.

That being said, any mileage hit you may take
is probably more attributable to other aspects
of the tire, verus just increased tire size. For
example, if you bought a larger size, but it
was a particularly good "low rolling resistance"
tire, you could easily get improved mileage. Or,
if you buy a crummy tire to begin with, you're
likely to take a hit no matter what.

And of course, if you increase your tire pressure
beyond the 35-ish psi recommended on the door
sticker, you get way more improved mpg than
any increased tire size mpg loss.

 

Your wheel size with the 195's will be 24" vs 24.3" with the 185's
but your tread width will go up from 5.8" to 6.3", so you will lose a little bit in terms of MPG but you will gain stability and in my opinion have a safer ride.
The dealer isn't necessarily the place to replace your tires, do a quick search of your area for dealers, to buy from discount tires online gives free shipping, most tire dealers charge 12$ per wheel to install.

 

If you're getting new tires, I highly recommend researching some apples to apples tire tests.

The two most recent and best tire tests are Consumer Reports' November 2009 comprehensive tests of a wide variety of tires, and TireRack.com's August 2009 test of several, mostly low rolling resistance tires mounted on a Gen II Prius.

Here's a 2-page scan of Consumer Reports' November 2009 tire test Recommendations and Ratings:

Consumer_Reports_Nov._2009_Tire_Tests-1.doc

And here's a link to TireRack.com's tests of low rolling resistance tires on a Prius (but note that TireRack did not test the tires in snow or on ice):

When Round and Black Becomes Lean and Green

Read the tire tests, consider all the factors (handling, braking, wet performance, snow performance, rolling resistance, etc.) that are important to you and choose your tire.

Note that many of the tires do not come in your Prius OEM tire size of 185/65R15, but are available in the next closest size of 195/60R15 which I have on my Prius.

* * * * * * *

If I were in the market for new all-season tires, I would get the Hankook Optimo H727 in the 195/60R15 size. They're among the highest rated all-season tires tested by Consumer Reports. They have snow traction and ice braking performance equal to or better than most winter tires tested by Consumer Reports. And they're relatively inexpensive -- about $300 for 4 (free shipping & no tax) from Gripston.com, plus you get a $30 rebate for a total price of about $270:

Gripston - Hankook

Note however that you'll probably lose about 2 mpg compared to your OEM Integrity 185/65R15 tires. And you'll have to find a place near you to mount and balance the tires.

* * * * * * *
Good luck.

 

Tom, When you went with the 195/60r15 tires did you need to buy new wheels?

 

No.

 

Will 195/65/15 work?

Can 195/65/15 be used on a 2008 Prius?
I have a chance for a 'new' set of Arctic Snows on steel rims for short money. Will these be OK to put on?

Thanks

 

My '06 came with 185/65-15's stock and their diameter is 24.5"
195/85-15's are 25", so 1/2" taller then stock, slightly better gas mileage, slightly slower starts, all good for snow and ice, yes the 195/65-15's can go on your '08, put studs in the new snows and be unstoppable...

 

195/65-15???

 

In the UK 195/55/16 is the standard tyre and rim size for the GEN2 Prius and some owners including myself use 205/55/16 tyres with no problems or major hits to fuel consumption. I am using Hankook K425 tyres and have gained about 1MPG extra to my OEM Bridgestone 195/55/16 tyres. My car is a 2008 Tspirit witch is a rough equivalent to the US Touring.

 

Not enough to worry about. But you shouldn't be looking at 195/60 tires anyway. That is the wrong size. You want 196/65 or 205/55 depending on the brand/model of tire.

Tires I'm recommending based on tirerack reviews and price and Gen II RPM of 845 and Gen III RPM of 835 are

General Altimax HP (not LRR, cheapest per tire that I recommend with excellent wet traction)
Gen II 15" choice $71 843 185/65/15 General Alimax HP
Gen II/III 15" choice $74 837 205/60/15 General Alimax HP
Gen III 15" choice $72 829 195/65/15 General Alimax HP
Gen II/III 16" $97 831 205/55/16 General Alimax HP.

Hankook Optimo H727 (better than average RR, still good pricing and better snow/ice ratings, best rated "Standard Touring All-Season" on tirerack)
Gen II/III 15" choice $74 831 195/65/15 Hankook Optimo H727
Gen II/III 16" choice $97 834 205/55/16 Hankook Optimo H727

Yokohama Avid ENVigor (better than average RR, the Hankook Optimo H727 is likely a better choice all the way around)
Gen II 15" choice $78 840 205/60/15 Yokohama AVID ENVigor
Gen III 15" choice $84 831 195/65/15 Yokohama AVID ENVigor
Gen II/III 16" choice $100 833 205/55/16 Yokohama AVID ENVigor

Goodyear Assurance ComforTred Touring (not LRR, don't confuse it for the Goodyear Assurance ComforTred (one says Touring the other doesn't) the non "touring" version isn't as good in the snow (among other differences). The touring version is the best rated "Grand Touring All-Season" on tirerack.
Gen II/III 15" choice $103 836 195/65/15 Goodyear Assurance ComforTred Touring
Gen II/III 16" choice $127 840 205/55/16 Goodyear Assurance ComforTred Touring


Michelin Pilot Exalto A/S (not LRR, rated as the best "High Performance All-Season" on tirerack.
Gen II/III 15" choice $101 832 195/65/15 Michelin Pilot Exalto A/S
Gen II/III 16" choice $115 839 205/55/16 Michelin Pilot Exalto A/S

So after all that no true LRR tires. What LRR tires would I recommend?

For 15" rims a LRR choice is the Michelin Energy Saver A/S (it's only "Passenger All-Season" but it's rated highly in that category)
Gen II/III 15" choice $95 832 195/65/15 Michelin Energy Saver A/S with Green X

If you have 16" rims the Michelin Primacy MXV4 is LRR in a size I'd recommend (not LRR at 15" sizes, rated just below the Goodyear Assurance ComforTred Touring in the "Grand Touring All-Season" category on tirerack.
Gen II/III 16" choice $138 837 205/55/16 Michelin Primacy MXV4 with Green X

Another LRR choice is the Michelen HydroEdge with Green X (it's only "Passenger All-Season", it has better wet/dry traction than the Michelin Energy Saver A/S but worse snow/ice traction). May be harder to find.

Gen II 15" choice 849 $105 205/60/15 Michelin HydroEdge w/ Green X
Gen II/III 15" choice 832 $104 215/60/15 Michelin HydroEdge w/ Green X

There are other LRR choices in the thread by F8L but they aren't All-Season, or aren't sold on Tirerack, or just don't have enough purchases on tirerack to get survey data.