Tire Question - 2000 Forester

[howards11]

The standard tires on the 2000 Forester L are 205/70R15. I friend said that when I replaced the tires in November 2008, I should have upgraded to the next size, 215/70R15. His reasoning is that I would get better gas mileage and better handling. Is he correct or not.

 

~Howard

[Rooster2]

Maybe a little better handling. Figure on your Forester standing just a little taller off the ground on the bigger tires, so ground clearance may go up about an inch. Gas millage should not change much at all. Spedo will read about 2 miles per hour slow. One size larger tires should fit just fine. Acceleration will be a tiny bit slower.

[Fairtax4me]

No on both. The wider footprint and larger diameter will both work against you for the fuel mileage. Ask someone with a pickup on 32" mud tires how their mileage is compared to their old stock tires.

And while the wider tire may hold an extra centimeter of road underneath it, the taller sidewall will fold more, and negate any desirable effect the added width might produce.

Not only that, larger tires generally cost more. You're probably looking at an average of $5 more per tire for that size compared to stock.

 

If you want better handling, you get a larger wheel with a shorter profile tire to reduce sidewall flex.

If you want better fuel economy, you get a skinnier tire. The thinner foot print means less friction on the road, which means it rolls easier. But it will also be harder to stop.

[OB99W]

[...]ground clearance may go up about an inch.[...]

Ground clearance would go up, but by considerably less than an inch. The increase in width is 215mm minus 205mm, or 10mm. The ground clearance change would be 70% of that (from tire aspect ratio), or 7mm -- that's a bit more than 1/4''.

[Scoobywagon]

you might see MARGINAL mpg increases from a larger tire, but not one that is larger in the dimension you specified. You'd go from 205/70R15 to 205/75R15 or 205/80R15. This leaves your contact patch the same size but gives you an overall taller tire. Handling will suffer for it as will acceleration.

 

If you are trying to maximize fuel economy, try keeping the tires the factory size, but go to a harder rubber compound. That reduces rolling resistance. Again, you will lose a small percentage in handling and braking performance.