narrower wheels and tires?

[steve-o]

i am thinking of trying to find some narrower tires for the paseo, i am thinking that a set off of a tercel will bolt right on. if i have on 185/60/14's on now and go to a 155/80/13 what can i look for in mpg gains?

[mwebb]

Originally Posted by steve-o

i am thinking of trying to find some narrower tires for the paseo, i am thinking that a set off of a tercel will bolt right on. if i have on 185/60/14's on now and go to a 155/80/13 what can i look for in mpg gains?

the "gains" will be measured in negative Numbers.
and
do not forget to recalibrate your speedometer / Odometer against a GPS for speed and against highway mile markers for distance

use the recalibration for calculating FE per tank

it (FE) will get worse

[mcrews]

handling will suffer....noticeably

[CapriRacer]

Tire size does not have much of an effect on rolling resistance, but directionally, tires with larger load carrying capacities have better RR - in spite of the fact that they may be wider!

Steve, you are going the wrong direction!

- BUT -

THE most important thing when it comes to rolling resistance in tires is the tread compound. It can have a profound affect (up to 60% worst to best)

The problem is that Rolling Resistance / Treadwear / Traction (especially wet traction) tradeoff with one another. Tires that get great rolling resistance are bad for treadwear and / or grip.

You would be further ahead putting the largest tire you can fit inside the fenderwell without rubbing, then selecting a tire that has the proportion of RR/wear/traction that you want.

[Patrick]

Originally Posted by mwebb

the "gains" will be measured in negative Numbers.
and
do not forget to recalibrate your speedometer / Odometer against a GPS for speed and against highway mile markers for distance

use the recalibration for calculating FE per tank

it (FE) will get worse

Actually, the two tires are almost exactly the same diameter.

OP, you may gain a little mpg due to the lower aerodynamic drag of the thinner (155) tire. There also may be a benefit if the new tire has a higher max pressure (i.e. 51 psi vs. 44 psi), resulting in lower rolling resistance.

Make sure the new wheels will clear the brake calipers.

[mwebb]

Originally Posted by Patrick

Actually, the two tires are almost exactly the same diameter.

OP, you may gain a little mpg due to the lower aerodynamic drag of the thinner (155) tire. There also may be a benefit if the new tire has a higher max pressure (i.e. 51 psi vs. 44 psi), resulting in lower rolling resistance.

Make sure the new wheels will clear the brake calipers.

almost ...
but there are no 13" LRR tires and the 185 60 14 will almost certainly have lower rolling resistance than the 13 " tire

at the same tire pressure

wider - is better for LRR but worse for drag
ever see a 155 80 13 on a prius or insight ? i never did .

[steve-o]

ok since it looks like i am going the wrong way with the tire thing, i was looking to lower my drag with the narrower tires, should i look into blocking off air to the front of the car? if so do i block off parts of the bottom of the grill(under the bumper) first or should i look somewhere else? i am kind of looking for a priority list of how to improve mileage quickly. i did all the normal tune up stuff and took up tire pressure from this i saw about 5% pick up, as a test i put some duct tape across the grill(above the bumper). am i on the right track and what obvious stufff did i miss?

[born2pdl]

It may not be that clear cut. Take this reverse example. My metro stock tires were 155-80-13. I went to 175-65-14 and lost 3~4 mpg. But the ride, handle and look are quite a bit better. I agree that 13's probably wouldn't fit over your brakes.

But I'm not convinced that 175-65-14 or something wouldn't be just fine. Only if you need new tires. Cost of changing tires just for mpg purposes is ridiculous, you never save enough gas to pay for the tires.

[steve-o]

Thanks born2pdl,
i was looking at tires and rims and thinking that the paseo and tercel are basically the same car so if i could get a set of wheels off a tercel they should have the right off-set for my car. now that i think of it there are some pretty good you-pull-it scrap yards that are pretty cheap to get a set of wheels. i am not really worried about looks or handling this is my "work car" that i drive only about 95% of the time.

[MARTINSR]

I know NOTHING about LRR and all other than the common sense the good Lord gave me and that seems to be thrown out the window when we start talking about this. I picture the taller and narrower the tire the lower the rolling and wind resistance, end of story. But it isn't as simple as that is it.

I know that I plan on running my bias ply white walls on my Rambler until I need a set (or just get tired of the look) and get myself some aluminum wheels and LRR radials for it. I will have to do a lot of studying before I jump into that pool though. Right now it has 5.90-15's on a 15x5 steel wheel.

Now, honestly, with that little contact area, I would think these tires at the recommended air pressure would be pretty darn low LRR! What do you experienced guys think?

Brian

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