Mythbusters tire pressure testing: +5 psi = 6% fuel savings

[jpa2825]

For those of us too lazy to get the gauge out of the glove box, any loose recommendation of how long after the LEAF beeps at you and flashes the lights you should keep putting air in to get +5 psi? I usually go up to 5 or so seconds beyond the beep & flash.

Also, what model trims have the beep & flash for air pressure? I think it is a really cool & useful feature.

 

[apvbguy]

For those of us too lazy to get the gauge out of the glove box, any loose recommendation of how long after the LEAF beeps at you and flashes the lights you should keep putting air in to get +5 psi? I usually go up to 5 or so seconds beyond the beep & flash.

don't be lazy and use the gauge, you cannot be any kind of accurate going by your method, every machine pushes air at different levels and the heat of the tire also will have an effect.
YMMV

 

[Nubo]

For those of us too lazy to get the gauge out of the glove box, any loose recommendation of how long after the LEAF beeps at you and flashes the lights you should keep putting air in to get +5 psi? I usually go up to 5 or so seconds beyond the beep & flash.

That's totally dependent on the rate at which your particular pump is delivering. I would not use that method, or at least calibrate it with the specific pump you use, and an accurate tire gauge so you know how many psi/sec are being delivered. But that could change over time and since you need an accurate tire gauge to do the calibration anyway, why not just use it all the time? I prefer the ones with a bleed valve; this is very convenient because you just overshoot a bit and then easily dial in the exact pressure you need without repeated rounds with the pump.

https://www.sportys.com/Pilotshop/product/9066

 

[LEAFfan]

For those of us too lazy to get the gauge out of the glove box, any loose recommendation of how long after the LEAF beeps at you and flashes the lights you should keep putting air in to get +5 psi? I usually go up to 5 or so seconds beyond the beep & flash.

That's totally dependent on the rate at which your particular pump is delivering. I would not use that method, or at least calibrate it with the specific pump you use, and an accurate tire gauge so you know how many psi/sec are being delivered. But that could change over time and since you need an accurate tire gauge to do the calibration anyway, why not just use it all the time? I prefer the ones with a bleed valve; this is very convenient because you just overshoot a bit and then easily dial in the exact pressure you need without repeated rounds with the pump.

https://www.sportys.com/Pilotshop/product/9066

I've never found any of those inexpensive gauges to be at all accurate. They show 4-6 lbs. under. The most accurate gauge I've used is a Milton pen type.

 

[Nubo]

I've never found any of those inexpensive gauges to be at all accurate. They show 4-6 lbs. under. The most accurate gauge I've used is a Milton pen type.

Are you dissing the Bourdon Tube? :lol:

 

[kubel]

yeah, I over-drove the tires a bit!

Something is seriously wrong with those tires.

 

[Nubo]

yeah, I over-drove the tires a bit!

Something is seriously wrong with those tires.

Singing takes a lot out of them. :lol:

 

[derkraut]

It appears that you have some significant alignment and/or tire pressure issues there.

 

[DaveEV]

Something is seriously wrong with those tires.

That is what happens to all-season tires when you auto-x all day on a course with a couple of big sweepers in one direction and then push the car too hard scrubbing the tires. The other three tires were also significantly worn, but not nearly as bad as this one - it took the brunt of the abuse that day. The alignment on the car was fine - very even wear with just a bit of outside shoulder wear despite -1* of camber. Before the day started they looked a bit worse than TomT's pic above despite having half the miles that TomT has on his.

I still managed to turn in some good times despite the fact that the tires had no grip even compared to cheap-o summer tires (I rode in a few other WRXs with different tires). The lack of grip tends to encourage one to push them a bit harder than they should be. That's why I question TomT's claim that the MXV4s are night and day better than the Ecopias. Personally I feel they are basically the same compared to summer tires.

Anyway, just my 2c. I did not care for the tires much at all (the only thing I liked about them is that they were pretty quiet), so I wasn't sad to see them get chunked up like that.

 

[TomT]

I think you have to look at within the context of LRR tires... I don't know of any true LRR tires that have much grip when compared to any high performance tire and they would be my last choice for autocrossing (which I have done a fair amount of over the years, but not in the Leaf)... However, viewed simply as LRR tires, I found them to be a big improvement over the OEMS in things such as wear, ride, handling (within limits), and robustness. But yeah, measured by the same standards that I would use for, say, my BMW, that are severely lacking...

That's why I question TomT's claim that the MXV4s are night and day better than the Ecopias. Personally I feel they are basically the same compared to summer tires.

 

[mwalsh]

Was trying to decide where to post this observation, and this tire related thread seems as good a place as any.

This weekend I found a time where 40psi in my tires didn't really work out for me (or my passengers) - a fully occupied car, vs. a car with just myself, or myself and the wife, gave a very jarring ride indeed. This morning (just me) it's back to feeling "normal" again. I wouldn't have thought the extra weight of two teenagers would make that much difference. Though the one is over 6' tall and must weigh at least the same as I do (and his weight isn't from a beer gut!).