Tires

Response to excessive fuel consumption on Subaru
Posted by Daniel on December 6, 2006

Original Question

I recently bought new Michelin Pilot tires for my 2003 Subaru outback which were recommended to me from several sources. I am very disappointed so far. After 1500 miles on them my gas mileage has dropped by aprox 5 mpg. Since I drive 100 miles a day this is a substantial amt. of money over time. Is this normal for tires to cause this much decrease in mileage?

A. I’m guessing that you are seeing something like a 15 - 20 % loss in fuel economy with this tire change. I think there is something else affecting this besides tires. Have the vehicle checked out by a good mechanic.

Toppin answer…

This issue I am sure is related to either inflation pressures or a different rolling radius of the new tires. Try checking you tire pressures first. Keep inflating them to a maximum of 38 PSI or until ride quality becomes unacceptable.

You may then want to check your speedo calibration. Rolling radius will effect percieved MPG significantly when making tire changes, ieven if the width and aspect ratio are identical, you will find actual rolling radius varies significantly from manufacturer to manufacturer even with the same size tire. If either of these do not solve this, something else is going on with engine tuning. Hope this helps .Toppin

Tires Selection
Posted by Nelson on December 6, 2006

I am a package car deleivery driver along with 20 other drivers in the northern California. We have a lot of snow in our rural area every year. Our company recently changed all the front steer tires on our delivery trucks using Goodyear G149 RSA and we just had our first wet snow storm last week with few inches wet snow on the ground I noticed my front end was all over the place with no control whatsoever. I cannot remember I have that much control problem with the tires we used to have (G133 or G124). Would you recommend using the G149 RSA for our snow rural area?