Tire Width

[louisb323]

I'll be due for new tires soon and was thinking that switching to thinner tires my help in fuel efficiency. Does anyone know if and, if so, how much that will help?

[LostCause]

Read up on this thread.

The theory goes that you want a square contact patch running at the highest PSI your tire will allow. I'd go measure your contact patch of your current tires at max sidewall PSI. If it is undersquare, go skinnier. If it is oversquare, stay put.

Stuff gets complicated with changing contact patch geometry (turns circular at higher PSI) and uneven weight distribution in the car. The ideal situation would probably be running different width tires front and back.

This theory has never been tested, so take it for what it is worth. If you are in the market for new tires, I'd go for LRR models.

- LostCause

[Johnny Mullet]

What size are you running now?

[louisb323]

215 50r17

[ebacherville]

there is a you tube test video around here somewhere that a guy put 2 doughts on the rear of his accent and its significantly make a large gain in MPG.. HOwever those little 110mm tires dont perform well for handling.. and its really the matter of the car , a geo metro or CRX may be able to easily use 135-13"s safely (heck the geos came with 12" tires... but put them on a 3000 lbs yaris and it will handle like its on marbles.. its all about the car.. your mileage may vary..

However the less contact patch hitting the road is almost always going to be more efficient.. but handling may suffer depending on the car.. thus why many over inflate there tires to get less patch on the road.

[louisb323]

Well, atm I don't need a lot of handling (98% of my driving is mostly straight freeway miles) and if/when I do I would just swap out my old (wider) wheels/tires with the thinner ones. (I would have two sets.)

I work for an auto group so maybe I'll see if I can get some steel wheels (that might have been upgraded to customs) for cheap.

[Daox]

I'd probably go with the skinniest tires that Toyota recommends for the car.

[beatr911]

louisb323, we went from 225/60-16 to 215/65-16 on our Odyssey. Handling was only a little less precise probably due to tire design more than anything else. Max lateral grip is almost never tested anyway so it isn't really a factor. As the wife doesn't always check mileage and drives it 90% of the time it's hard to get a good reading. Based upon our log it is looking like an average of less than .5 mpg but this also factors in different tire design so it is a pretty sketchy number.

Lots of little things add up, this one will help but you'll never see a big mpg increase from tires.

If you can, do a comparison and post it. It would be beneficial for everyone if you could post a comparison between what you've got now and a LRR tire that is 1 or 2 sizes skinnier. I would think the difference would be measurable and beyond the background noise of the test itsself. If you can't find a LRR tire, select whatever skinnier tire and compare, not all of us can find LRR tires in the required size iether.

Personally, I buy good used tires in sets from our local used tire dealer. Like 1/4 the cost of new, way more cost efficent than even a LRR tire. Yeah, I'm cheap.

[Johnny Mullet]

See if the car had optional 16" rims and it would be easier to find skinnier tires in a 16" size compared to a 17" size.