Low Rolling Resistance replacement tires: Current List

Not long after buying the 422s' we took the YARIS out for a test drive in the rain and they did fine . Just need to slow down a bit . Yesterday we went for a trip and F.E. is up . The Eco-Meter is reading about 1 m.p.g. less than the calculated gas mileage , so it may be 42 m.p.g.. E.M. is at 95 , may have to reset to 96 . The ride was very hilly and winds were up to 30 m.p.h.. Temp in mid > upper 40s' . A few state roads are quite curvy and the the tires handled quite well . Tires set at 36 p.s.i.. . There's less than 800 miles on them . The YARIS has a 4 speed auto .

 

I had the Ecopia 422 on my civic before and they handled the WA daily rain pretty well, like you mentioned "Drive slow." Definitely not a tire that I would push in the rain or splash water on a puddle as it does not do very well hydroplaning. The Michelin MXM4 that I have now keeps me pretty comfortable driving highway speed limit during heavy rain, and water puddles are just good fun

 

Need help from F8L. I just bought a new to me used 2006 Prius with 102,000 miles on it. The vehicle has been exceptionally well maintained at the Toyota dealership and has all records. It runs like a dream, but only gets 41 mpg. I live in a flat area, that averages 68 degrees. Most of my drives are below 60 mph and average about 30+ miles each way. I'll spare you the list of things I've done to improve mileage, but they include employing pulse and glide driving techniques to checking/replacing parts on my car. So far nothing has made a difference in mileage.

The car has brand new tires on it -- BF Goodrich Advantage T/As. I've read these aren't the best tires for the Prius, but I've also read other Prius owners with these same tires averaging nearly 10 mpg better than I am. I run the tires at 44/42 psi. How much of a difference can these tires have on my MPG? Are they the likely source of my mpg problems?

 

I suggest you check the 12v battery. If your car has the original battery it probably needs to be replaced. An old/weak can cause the ICE to run more and lower your mpg.

 

The battery was replaced in January of 2010. Since then it has 30,000 miles on it. I checked it using the display and it registered 12.3 volts after sitting overnight. Put a load on it in accessory mode (HID headlights, front and rear defroster, heater) and it came in at 10.9 volts. Not sure how to interpret that, but do you think it warrants replacing the battery?

 

I suggested the OP get advice from you. The tyres are rated E for RR in the UK, also being new tyres will give even more of a hit in mpg. These tyres were fitted by a dealer, so no surprises there.

John (Britprius)

 

Thanks F8L. The ICE rarely idles at stoplights. I may just replace the battery to cross that off the list. The only other thing is tires. How much should I expect to gain if I go to the Energy Savers. If I do that, I'll take your suggestion and sell the BF Goodrich tires (have 500 miles on them). I just don't want to go that route unless it really makes a difference in MPG. Thanks again to you and everyone who is trying to help me with this.

 

Sorry, but I forgot to answer one of your questions. I live in San Luis Obispo, CA.

 

Just replaced my tires lately with the Michellin Defenders per Discount tires suggestion. I was dropping MPG's with it as soon as got out of their building and was planning to replace it with the Bridgestone ecopia's the next day. Rep checked tire pressure and was at Toyota specs @ 35 and 33 psi. Rep said to try higher psi before replacing tires. Set front psi to 38 and 36 for rears. Tried it for a day and was much better and stick with the defenders. Been buying tires from them for years and couldn't ask for better customer service. They were willing to replace the defenders with the ecopias without hesitation.

 

You might check the oil level - overfilling and/or using the wrong oil can cost 4-6 mpg. I had that happen a Speedy-lube once on my 2008 Gen II.

The difference between 40 mpg and 45 mpg amounts to about $115 per 10,000 miles of travel ($4 a gal for gas).

 

In the UK tyre choice is even more critical with our price for petrol (gas) being more than double your figure, meaning the tyres can pay for themselves in less than 15,000 miles with the correct choice.

John (Britprius)

 

xpcman, I changed the oil myself to 0-20w synthetic as recommended by the dealership. I knew about the overfill issue, so I was careful to fill it to just a tick below the full line.

F8L, in my reply to you above, I meant to ask if you recommend going to a 195/65/15 from a 185/65/15 on a gen II (posted the wrong tire size by accident).

What are most people with the gen II Prius averaging? Just trying to figure how far off I am.

 

In the UK the Prius comes with 195/55/16 tyres. I have gone up to 205/55/16 with an improvement in all aspects including mpg. More details if required.

John (Britprius)