Quote:
Originally Posted by MPGee
Hi all,
I'm getting close to needing new tires on my '07 Toyota Matrix. I'm running factory 16" steel wheels with factory size tires. I'm considering going to '07 Corolla 15" steel wheels. I believe my #s for the below are correct:
Existing stock Matrix wheel/tire:
205/55R16, 16x6.5" steel wheel, 5x100 bolt pattern, 39mm offset
Proposed stock Corolla wheel/tire:
195/65R15, 15x6" steel wheel, 5x100 bolt pattern ?? offset
See attached photos for calculator results from rimsntires.com's calculator (I can't post links, b/c I'm a n00b.  )
How much gains do you think I can expect from getting a 10mm "thinner" tire and -1" on rim size? The calculator says that the 15" wheel+tire should be ~3 lbs lighter.
I drive, maybe, 40% city, 60% highway. I would be trying to get some Corolla steelies used or from the junkyard.
Thx in advance. |
based on the original info, I wouldn't expect any mpg increase.
But here is how to tell.
Remove your spare and 20 more pounds from the car. That would equal the weight saving and the rolling momentum from lower weight wheels.
Do an A-B-A test in a 10 mile section w your scangauge.
Now you have your answer.
the 10mm thinner is nothing on the aero side. Weight only really counts at start and stop. The new tires are effectively the same height so no gearing advantage.
Question: why go to all the trouble for almost no mpg improvement and not go whith a 5% taller tire?
it has been proven to increase mpg in A-B-A tested cars.
with 60% of your driving on the freeway consider lowering the rpms. That's where the rpm improvement comes from.