tire size - gas mileage?

[Nanda]

Hellow folks,

I'm about to buy new tires and thought a larger tire might yeild a little better mileage, but that's just my speculation. I know tires make a differnce because when I got the last set, the tires were a bit wider and cost me at least 1 mpg. I've got a 99 maxima that takes 205-65-15's, but I believe 205-70-15's will fit. The 70's are about 1" bigger in diameter but they weigh almost 1 lb. more. Maybe if I go smaller with a 195 65 15 and narrower I'd get better mileage. I'd appreciate all help. Thanks

 

[UncleS2]

195/65/15 should be about 1/2" shorter(less than 2% difference), probably a good choice. You might also consider a 195/70/15 if you can find them. Nominally only about 1/4" taller than 205/65/15(ie, real world no noticeable difference), it'll be a little narrower & should work well at good tight air pressure, say 35-37 psi. Ck for rolling resistance info if available too.

 

[Smokescreen]

Not always. If your stock tire size already is in the sweet spot for rpm you might actually lose mpgs as the motor will drink a little more especially if you have hills or stop and go traffic. If you have lots of flat highway it could save you a couple of mpgs. As you discovered wider tires will cost you, more friction, more to slice through the air. Make sure you consult this first to see more precise idea: http://www.miata.net/garage/tirecalc.html

 

[HTSS_TR]

Originally Posted By: Stuart Hughes
195/65/15 should be about 1/2" shorter(less than 2% difference), probably a good choice. You might also consider a 195/70/15 if you can find them. Nominally only about 1/4" taller than 205/65/15(ie, real world no noticeable difference), it'll be a little narrower & should work well at good tight air pressure, say 35-37 psi. Ck for rolling resistance info if available too.

I agree.

The size 195/70/15 will give you better MPG and better performance on wet streets, but it will reduce the performance/handling on dry surface.

 

[Nanda]

Thanks for the quick info. That answers my question. Scratch the 205/70/15's. I searched for 195/70/15's but they are pricier and heaver. I found some Continentals about $20 a piece more and they were 4 lbs heavier with a load range D, maybe recommended for vans and trucks. 4lbs heavier cant be good for mph or the transmission. Any thoughts about the 195/65/15's? Thanks again

 

[Hokiefyd]

If your OEM tire is a 205/65R15, the 195/65R15 won't have the required load index. Otherwise, I think they'd be a good choice. And there are a ton-and-a-half good tires available in that size.

 

[HTSS_TR]

The problem is, the 70 series tire is mostly for small SUV/truck and very few available. The 60 and 65 series are very popular tires now, many models to choose from and the price is very low too.

Your OEM 205/65-15 has a load range of 1400 lbs per tire, 195/65-15 has a load range of only 1279 lbs, these load ranges are taken off the Yokohama AVID TOURING-S specs.

Your Maxima with 195/65-15 will have a total load capacity of 500 lbs less than the OEM 205/65-15.

I would stay with OEM size 205/65-15 and pump up the pressure to about 6-8 PSI above the placard to improve the MPG, the ride will be firmer than recommended pressure but you don't loose the carrying capacity of your Maxima.

 

[4ever4d]

Going narrower may help your mpg but smaller diameter will increase your rpm's sightly could possibly end up being a wash and not really gaining anything.

 

[CapriRacer]

Originally Posted By: Nanda
Hellow folks,

I'm about to buy new tires and thought a larger tire might yield a little better mileage, but that's just my speculation. I know tires make a differnce because when I got the last set, the tires were a bit wider and cost me at least 1 mpg. I've got a 99 maxima that takes 205-65-15's, but I believe 205-70-15's will fit. The 70's are about 1" bigger in diameter but they weigh almost 1 lb. more. Maybe if I go smaller with a 195 65 15 and narrower I'd get better mileage. I'd appreciate all help. Thanks


Long Version:

http://www.barrystiretech.com/rrandfe2.html

Short Version:

Directionally larger tires are better for rolling resistance. However, the difference is small and compared to the difference between tires, not enough to worry about.

But going smaller is not only the wrong direction for fuel economy, it's also the wrong direction for safety - heavily loaded tires are more likely to fail.

So your best bet is to stay with the same size, and carefully select your tires to do what you want them to do. Just be aware that Treadwear, Traction, and Rolling Resistance are tradeoffs. You have to decide in what proportion you want those and act accordingly.

 

[Nanda]

Thanks all,

After all the hella-ballow I staying with the stock size. I going with either the toyo estensa a/x or the yoko trz. The toyo's are a little cheaper.

 

[eljefino]

I wonder if you lost MPG on your last set just because of the thick new tread scrubbing all over. You rarely hear of someone getting better MPG from a new set of tires.

 

[kkreit01]

Stick with your stock size, and pick an LRR or "GreenX" tire if you want better mpg.