New tires = big hit to MPG thoughts?
#1
09-04-2007, 05:56 AM
New tires = big hit to MPG thoughts?
Ok so we have nearing 45k on our 07 TCH. A couple of weeks ago my wife hti something along the road and totaled her right front tire (big hole in the sidewall). Because of the milage and the need to get at least 2 tires (to avoid damage to differential) we decided to get 4 new tires. So off the stock Michelins and got new Good Year Triple treads because they are rated better in most catagories. Well the wet and dry traction are great...the ride seems quieter...and we have taken a 3-4 mpg hit in our fuel economy...formerly running 37-39 mpg and now 34-36 mpg....still good but not great.
The other day we were passing a radar stand (those deals the police put along the road to tell you your speed and get you to slow down) and while the speedo said ~26-27 MPH the sign said 23 MPH...before (old tires) these things would be closer...so I am guessing the new tires are different enough in dia that it is throwing things off...but with the speed info doesn't that mean my miles should now be over reporting? Or do I have my math off some place?
The other day we were passing a radar stand (those deals the police put along the road to tell you your speed and get you to slow down) and while the speedo said ~26-27 MPH the sign said 23 MPH...before (old tires) these things would be closer...so I am guessing the new tires are different enough in dia that it is throwing things off...but with the speed info doesn't that mean my miles should now be over reporting? Or do I have my math off some place?
#2
09-04-2007, 06:15 AM
Re: New tires = big hit to MPG thoughts?
. . .
The other day we were passing a radar stand (those deals the police put along the road to tell you your speed and get you to slow down) and while the speedo said ~26-27 miles per hour the sign said 23 MPH...before (old tires) these things would be closer...so I am guessing the new tires are different enough in dia that it is throwing things off...but with the speed info doesn't that mean my miles should now be over reporting? Or do I have my math off some place?
The other day we were passing a radar stand (those deals the police put along the road to tell you your speed and get you to slow down) and while the speedo said ~26-27 miles per hour the sign said 23 MPH...before (old tires) these things would be closer...so I am guessing the new tires are different enough in dia that it is throwing things off...but with the speed info doesn't that mean my miles should now be over reporting? Or do I have my math off some place?
In your case, it is good that your indicated speed appears to be lower than the actual. However, you really need to know how accurate your trip meter miles are to accurately calculate mileage and any speed correction factors.
GOOD LUCK!
Bob Wilson
#3
09-04-2007, 06:57 AM
Re: New tires = big hit to MPG thoughts?
Ok so we have nearing 45k on our 07 TCH. A couple of weeks ago my wife hit something along the road and totaled her right front tire (big hole in the sidewall). Because of the milage and the need to get at least 2 tires (to avoid damage to differential) we decided to get 4 new tires. So off the stock Michelins and got new Good Year Triple treads because they are rated better in most catagories. Well the wet and dry traction are great...the ride seems quieter...and we have taken a 3-4 mpg hit in our fuel economy...formerly running 37-39 mpg and now 34-36 mpg....still good but not great.
The other day we were passing a radar stand (those deals the police put along the road to tell you your speed and get you to slow down) and while the speedo said ~26-27 miles per hour the sign said 23 miles per hour...before (old tires) these things would be closer...so I am guessing the new tires are different enough in dia that it is throwing things off...but with the speed info doesn't that mean my miles should now be over reporting? Or do I have my math off some place?
The other day we were passing a radar stand (those deals the police put along the road to tell you your speed and get you to slow down) and while the speedo said ~26-27 miles per hour the sign said 23 miles per hour...before (old tires) these things would be closer...so I am guessing the new tires are different enough in dia that it is throwing things off...but with the speed info doesn't that mean my miles should now be over reporting? Or do I have my math off some place?
Bob Wilson is correct about checking the specifications on your old and new tires. You need to match or exceed the load rating (for safety) and you should also come close in revolutions per mile (to maintain speedo-odo-MPG consistency). I also will never buy a tire that is not H rated or above. H rated tires are generally much better construction than S or T rated tires.
JeffD
#4
09-04-2007, 07:15 AM
Re: New tires = big hit to MPG thoughts?
I forgot to mention, did you get a printed alignment sheet? The reason is the front wheel toe can be manually set, camber is harder and caster very difficult. But toe and camber do impact rolling resistance.
The real problem is the rear wheels are fixed. There is a Toyota alignment process for the rear axle but it involves a complex tool and often, they recommend replacing the rear axle, a terribly expensive affair. However, if you have the alignment printout, there are shim-kits that can bring the rear alignment to pretty much optimum.
You mentioned having a road impact causing at least one or more tires to fail. Such stresses can easily throw the alignment off. But do get the printed alignment sheet even if it means going back to get it done and printed out. Better to fix an alignment problem now rather than after losing tire rubber and wasting gas.
Bob Wilson
The real problem is the rear wheels are fixed. There is a Toyota alignment process for the rear axle but it involves a complex tool and often, they recommend replacing the rear axle, a terribly expensive affair. However, if you have the alignment printout, there are shim-kits that can bring the rear alignment to pretty much optimum.
You mentioned having a road impact causing at least one or more tires to fail. Such stresses can easily throw the alignment off. But do get the printed alignment sheet even if it means going back to get it done and printed out. Better to fix an alignment problem now rather than after losing tire rubber and wasting gas.
Bob Wilson
#5
09-04-2007, 08:05 AM
Re: New tires = big hit to MPG thoughts?
Please someone correct me if I am wrong, but I suspect the Camry Hy has a fully independent suspension at all four corners with no "rear axle" to deal with. This should make rear alignment concerns less dramatic, no?
Cheers;
MSantos
Cheers;
MSantos
#6
09-04-2007, 08:23 AM
Re: New tires = big hit to MPG thoughts?
I was thinking Prius and I don't know enough about the Camry suspension other than a general rule that after a tire damaging road incident, check the alignment and get the printout. I learned that our local shops were quite happy to be 'mum' about their inability to deal with rear wheel Prius alignment. The alignment printout solved that problem.
Bob Wilson
#8
09-04-2007, 11:45 AM
Re: New tires = big hit to MPG thoughts?
What size was the old tires and what size are the new tires?
#9
09-04-2007, 11:49 AM
Re: New tires = big hit to MPG thoughts?
Bob Wilson
#10
09-04-2007, 02:48 PM
Re: New tires = big hit to MPG thoughts?
215/60R16 both stock and new tires are the same size.
