I took my 2009 Prius for its 40,000 mile service in June. In addition to the general service I got new tires. I had been getting, on average, between 48-51mpg. After service it dropped to 31-38mpg. Though due to travel I have only put on around 250 miles since the service. I took it back to the dealership today and they checked everything out -- nothing wrong. Though they did lower the tire psi. I"m guessing its the deep treads on the new tires???? How long will it take to break in the new tires or break free from whatever is dragging down my fuel efficiency? I am really distraught about the mpg!!! Y'know, why own a Prius if you're only getting 31-38? I love my Prius and was thrilled every day to see what my mpg was!!! O.k. What should I do? Any ideas?
New tires always hurt, and non-Low-Rolling-Resistance tires will hurt even more. Lower pressure also hurts. The wrong oil, or too high oil level, will also hurt. Please look through this questionnaire for more hints: Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new
Make sure the tires are inflated to 42 psi front, 40 psi rear, or even more. The dealers deflate them. New tires have a run in time and mpg will improve gradually. If the dealer disconnected the 12V battery, there will be a period of recalibration that will also result in improved mpg gradually.
PS: I live in South Florida, have always run the AC all the time, driving is mostly flat and I spend about 40 minutes on highway, 30 - 40 minutes suburban driving, and 30 minutes idling while waiting in the car pickup line at my kid's school. Today the dealership reduced the psi to 35! Should I go back and ask them to increase it?
Underinflated non-LRR brand new tires could drop you almost 10mpg depending on what tires you went from, how worn they were, what they were inflated to and what the new tires are. Combine that with an oil overfill and you could potentially see such a loss. Since you have not finished even 1 full tank I don't know that you can claim a specific loss with any certainty. I would finish this tank and compare it to your last tank in similar weather conditions and commutes.
This idle time, with AC running, can introduce a significant MPG hit that varies enormously with weather. No, don't ask them, do it yourself. This makes sure it is in your control, and is done correctly with cold tires. The drive to the dealership will warm them up an unknown amount, interfering with proper pressure adjustment.
The new tires are Doral SDL 65L ? I am sorry but I cannot check the oil. I am technically challenged, when it comes to cars Can someone please explain to me why the tire pressure needs to be 42/40? Why did they put it down to 35? Thanks, mia
I don't know much about that tire but I'm pretty sure it's a cheap non-LRR tire. I remember someone else here complaining about a loss in MPG with those tires. You might save about 100 dollars on the tires but then you'll spend hundreds more on fuel over the life of the tires. It's really something that's worth learning how to do Mia. Honestly it's not difficult, you just need someone to show you once and I'm sure you could do it easily. The difference in MPG between 35psi and 42 psi in not that huge. It does make a difference, but the main issue is probably the tires themselves. Overfilling the oil is another thing that can cause a loss of MPG. If it's only overfilled by a tiny amount then the effect is also only small. But if it's overfilled by a large amount (like 1/2" or more) then it can be very detrimental.
I found that it is well worth paying the extra money for LLR tyres as the extra cost is more than recovered through the lifespan of the tyre. Work it out. You have lost 15 mpg (or so) by changing to these new cheap tyres. How much does that work out costing you over a tyre life of 30,000 miles? And then double the savings to see how much I would save paying $8.50 a gallon
O.k. Well, the tires were put on in June. But due to travel I have not been driving the car most of the summer (Maybe 300 miles since then). Can I go back to dealership and ask them to put on LLR tires, if I agree to pay the difference in cost? Or is that totally crazy and inappropriate?
No that's actually a good idea Mia, I'd say give that a try. First off, get some recommendations here about what particular brand/model tires to get based on your driving conditions. You haven't listed your location, we need to know if you have warm or cold whether or snow and ice etc in order to give a good recommendation. There's plenty of people here really into tires and know which ones give the best MPGs. Post your location or climate information and we'll give some recommendations. Get a few different recommendations, because the dealership may not carry them all, but once you go there don't let them talk you into anything else.
What kind of tires did you settle for? Being inFlorida I don't imagine you went with a all season . A good summer LRR would be great with high PSI. H
Those tires are terrible. I would make the case that they are costing you too much money due to the loss in fuel economy and you want to replace them with Michelin Energy Saver A/S or Bridgestone Ecopia EP422. I don't know how safe those tires are. At $43/ea. I don't have much confidence in them.
Those tires are definitely not helping. If you're lucky the dealer left the car ON. Using gas while not moving = zero MPG, which kills the average for that one tank. Have someone show you how to measure and inflate the tires, and wait for a couple of tank fills of gas; things should get better.
