Tall tire test (taller gearing advantage offset by wider, heavier wheels/tires?)

[California98Civic]

I'm watching this idea with interest. And now I know how time-consuming testing the way this site advocates can be--and how frustrating. So thanks.

Originally Posted by SentraSE-R

I'll inflate all tires to the same inflation pressure, either 44 or 51 psi.

Maybe it is more important to work with the recommended design parameters? That gives your results greater applicability for folks on this forum (not me) who are unwilling to over-inflate. Not a big deal, something just to consider. More important, wouldn't the aero qualitis change for the car given the different sizes of the fronts and the constant size of the backs?

Originally Posted by SentraSE-R

I was hoping since the start of the test drive is only 4 miles from home, that I could consider all the tires cold when starting the test.

Why not drive to the site on your "C" test tires. Remove them to cool. Then drive your first test round on the "A" tires... all will get at least some chance to cool. Of course, if you could get bit by some radioactive spider or something, maybe you can carry your car that four miles.

[Bill in Houston]

Originally Posted by SentraSE-R

Does anybody know how long it takes to warm tires up?

Yeah, I wish I knew. I felt bad for bringing it up without knowing the answer.

Originally Posted by California98Civic

Why not drive to the site on your "C" test tires. Remove them to cool. Then drive your first test round on the "A" tires... all will get at least some chance to cool.

I like this idea.

As far as time, I hate to even say it, but it sounds like starting at 4AM might be best. But that is silly, so I say just do it early in the day, and then look at your A-A results to see how much change happened during the day. Your mileage will tend to improve as axles, bearings, and transmission warm up, too, so you needed to look closely at those two different A results anyway.

[SentraSE-R]

The mules' sidewall pressure will determine what I'll use, since the stockers are 44 psi and the newbies are 51 psi. The mules will make 2 of 3, so I'll change the pressure of the odd man out.

At 4 a.m., it's dark enough that I'd need to run lights, which would introduce another variable. I don't think I'll bother running on the C tires to the starting point, as I doubt it will be worth my time to swap tires for a 4 mile drive, when it's questionable whether the tires will even warm up. I will read inflation pressure and tire surface temperature (with an IR temperature) when I leave home, when I start each test, and when I end each test.

Starting the first A test with cold engine and bearings is going to mess me up, since all the other tests will have a warm engine and bearings. I think I'll run two A tests right off, to get the engine and bearings warmed up. Unfortunately, that's going to warm the tires up. I can't win for losing.

[California98Civic]

Originally Posted by SentraSE-R

I don't think I'll bother running on the C tires to the starting point, as I doubt it will be worth my time to swap tires for a 4 mile drive, when it's questionable whether the tires will even warm up. I will read inflation pressure and tire surface temperature (with an IR temperature) when I leave home, when I start each test, and when I end each test.

Starting the first A test with cold engine and bearings is going to mess me up, since all the other tests will have a warm engine and bearings. I think I'll run two A tests right off, to get the engine and bearings warmed up. Unfortunately, that's going to warm the tires up. I can't win for losing.

Don't discount the "C" tire idea just yet. If you drive around on the "C" tires long enough to warm everything up, you might solve all the issues in the best (still imperfect) form. Once all is warm, switch to your "A" tires and start your test, letting the "C" tires cool a while. Also, if you record the temps as you say, you'll know for sure whether all this was necessary. It would be pretty cool. More work, though.

[SentraSE-R]

I think you and Bill are right. I'll make the mules my C test tires. I need to calibrate them for distance, anyway, so I'll drive them to the test start, and through the ~10 mile test once for the distance calibration. That should get the drivetrain warmed up. Then I'll switch to the A tires to start the real testing while the mules cool down.

[SentraSE-R]

I'm on a trip to Utah in the xB. Averaging 51.1 mpg over the last 2 tanks & 900 miles. The 47 lb tire/wheel combo isn't hurting my mpgs, despite being 12 lbs heavier for each wheel, 10 mm. wider, & less aerodynamic. They look tons better than the stockers. I plan on fitting full moon or Hollywood flipper hubcaps on the stock steelies when they're on the car.

[California98Civic]

Originally Posted by SentraSE-R

I'm on a trip to Utah in the xB. Averaging 51.1 mpg over the last 2 tanks & 900 miles. The 47 lb tire/wheel combo isn't hurting my mpgs, despite being 12 lbs heavier for each wheel, 10 mm. wider, & less aerodynamic. They look tons better than the stockers. I plan on fitting full moon or Hollywood flipper hubcaps on the stock steelies when they're on the car.

Wow Darrell. I guess at steady speeds the weight is not such an issue. Maybe it even helps in coasting? I guess I still wonder about stop/go traffic a little but this is instructive. Thanks.

[arcosine]

is that the famous shoe tree in the back ground? At what speeds are you driving?

[mcrews]

Great shot....since some call their tires 'shoe' for slang!!!
That is LONG drive. I did it from sacto several years ago.

I am glad for the positive results!! I'm sure we amateur scientests are missing the 'mass in motion creates better mpg"!!!!!! lol

My concern is alway for the long term wear since I keep my cars for a while and drive a lot of miles in a yr.

But your have DEFINITLY shown that at some point (5% maybe) a taller tire in motion on a trip (ie highway driving) WILL overcome the other factors (width, drag) and produce better mpg.

[Moriene]

I would if bighorns came in 28s and there 27s are only in12"
I'm happy with the BHs just wish there was more size options
If I stay with 26s its 12" big horns but I'm wanting to run 28s
which with 14" rims it would have the same side wall as 26s on 12s