[boltadmin]

Tire pressures are a very important key to higher fuel economy. The higher the pressure, the lower the rolling resistance, the higher the fuel economy. The absolute minimum you should use is the driver’s side door or owners manual recommended tire inflation criteria. This is what the EPA and your car manufacturer sets tire pressures to during the EPA city/highway testing. MAX sidewall is what I would recommend for most as it is well within the safety limits of your car and tire and allows better FE than the pressure listed in the driver’s side door. I can discuss but cannot personally recommend upwards of 25% higher than MAX sidewall as there are legal constraints we all have to live with. That being said, 50 + #’s on a MAX Sidewall rated tire leads to even higher FE. Pros, higher FE, less tread wear, more even tread wear across the treads width, shorter braking distances in a variety of conditions, and in many cases, even better handling. Cons, higher NVH (Noise, Vibration, Harshness).

 

[Raymondjram]

In my vehicles, I have "touring" tires that have wider and softer sidewalls. Adding pressure will stiffen the ride a bit and save gas, but the wider sidewalls still reduce road noise and ride harshness. If you want just the maximum range, follow the tips above, but for best ride while saving energy, get softer or "touring" tires.

 

[Packard V8]

That being said, 50 + #’s on a MAX Sidewall rated tire leads to even higher FE. Pros, higher FE, less tread wear, more even tread wear across the treads width, shorter braking distances in a variety of conditions, .

As one with fifty years of tire experience, I'll agree to strongly disagree with the above in bold.

1. Higher than recommended tire pressures cause more tread wear in the center of the tread. Overall wear may be less, but it won't be more even.

2. Higher than recommended pressure means less rubber on the road, less tread compliance and thus greater braking distances.

jack vines

 

[PhilBo]

With 55 years of driving experience I am in agreement with Packard V8. Tire pressure that’s too high results in less tire touching the road surface. In turn, this creates a harsher ride as well as compromised traction and the ability to stop quickly. A tire overinflated by as much as 6 psi can be damaged more easily when tires run over potholes or debris. Over time, overinflated tires lead to excessive inner tire tread wear, decreasing the overall life of tires. The correct tire pressure ensures the maximum/correct amount of rubber is in contact with the road which improves handling, braking distance, comfort and safety. Better range is great but not when it compromises safety.

 

[raitchison]

It's a balancing act, higher pressures will definitely improve economy but as others have mentioned in addition to making the ride harsher it will actually reduce available traction. IMO this could be an issue with tires that already have marginal traction (such as the tires that came on our Bolt).

I do run a bit high, 43 on the back tires and 44 on the fronts, but I've replaced my tires with summer tires that have quite a bit more traction than the Bolt factory tires, at the expense of rolling resistance and efficiency.

 

[drdiesel1]

I've been running 50 psi since buying my Bolt. Tires are flat and even.
I get good range, good handling, and better tread life............YMMV!

 

[PhilBo]

I've been running 50 psi since buying my Bolt. Tires are flat and even.
I get good range, good handling, and better tread life............YMMV!

How many miles on your tires and do you have the Michelin Green X?

 

[TimBolt]

The Bolt has a combined rating of 119 MPGe.

That’s good enough for me.

I set all four tires to the recommended 38 psi.

 

[NewsCoulomb]

I run my Bolt EV at 42 psi cold pressure (max is 44 psi). Even with that, I often see tire pressures up to 47-48 psi during regular driving.

 

[JC Bolt]

Both my Volt and Bolt recommend 38 psi in all tires. That said, I'm comfortable running 40-45 psi cold on the Volt with its Max 50 sidewall limit and knowing that in Florida it is common to see pressures rise 3-5 psi after pulling out of the garage onto the hot blacktop roads on a sunny 95F day. But, with the Max 44 on the Bolt I've been keeping the pressure at 38-39. I don't want to lose any efficiency that I'm entitled to but I'm also risk averse!


I will also mention that I had a blowout on a OEM self-sealing tire on my 2001 Oldsmobile Silhouette minivan while driving on the interstate at 65mph. Don't recall the brand of those tires. Perhaps the technology has improved since then but when that tire blew, it sprayed the tarry sealant muck everywhere (even the windshield) and it was a mighty ordeal to remove. It took the tire shop hours just to get the rim clean enough to make a good seal on the replacement tire. I know it was hours because I was in the waiting room all that time and got periodic updates on all the methods and solvents they were trying to clean up the mess.

 

[drdiesel1]

How many miles on your tires and do you have the Michelin Green X?

23K. It has the factory tires and they still look like new!

 

[boltage]

As one with fifty years of tire experience, I'll agree to strongly disagree with the above in bold.

1. Higher than recommended tire pressures cause more tread wear in the center of the tread. Overall wear may be less, but it won't be more even.

2. Higher than recommended pressure means less rubber on the road, less tread compliance and thus greater braking distances.

jack vines

While that should generally be true, I had a car in the past where the OEM tires inflated to the pressures listed on the car showed underinflation wear patterns (more worn on the sides than the center). However, it is unlikely that the Bolt is that way to a significant level, since the recommended pressures of 38psi are not that far off from the OEM tires' sidewall maximum of 44psi.


It is also the case that pressures will vary significantly with driving, ambient temperature, and even sun shining on the tires (if you park the car on a sunny day with one side facing the sun, the tires on that side may show a few psi higher than the tires on the shaded side). I have seen differences of 5-6psi from the morning after a night in a garage to afternoon on a hot sunny day.

 

[raitchison]

As one with fifty years of tire experience, I'll agree to strongly disagree with the above in bold.

1. Higher than recommended tire pressures cause more tread wear in the center of the tread. Overall wear may be less, but it won't be more even.

2. Higher than recommended pressure means less rubber on the road, less tread compliance and thus greater braking distances.

jack vines

There's an old autocrossers trick that could help solve the question, take chalk (sidewalk chalk works well) and make a thick line across the entire width of the tire, drive a dozen or so feet then look at the chalk line to see if it's "wearing" evenly.

You need to be sure you're testing when the tires are at operating temp so drive at least several miles before you do it.

 

[dbostrom]

On a semi-related note, I'd like to try stickier tires on the Bolt at some point because so far my "sport mode" endeavors are limited strictly by tire traction.

I'll hazard a guess that running sticky tires at 6-7 PSI over doorjamb pressure will recoup some efficiency loss and will still yield better traction even if not quite as good as "normal sticky." So the end result is a choice between maximum traction (doorjamb) or a compromise between traction and efficiency at slightly boosted PSI. Easy to change back and forth.

Is there a canonical sticky/performance tire thread on the site already? I'm 100% sure this has been discussed in the usual depth, but which thread would that be? There are a number of seeming candidates.

 

[raitchison]

On a semi-related note, I'd like to try stickier tires on the Bolt at some point because so far my "sport mode" endeavors are limited strictly by tire traction.

I'll hazard a guess that running sticky tires at 6-7 PSI over doorjamb pressure will recoup some efficiency loss and will still yield better traction even if not quite as good as "normal sticky." So the end result is a choice between maximum traction (doorjamb) or a compromise between traction and efficiency at slightly boosted PSI. Easy to change back and forth.

I have summer tires that are not LRR rated, specifically Kumho Ecsta PS31s. They are indeed much sticker than the OEM tires but even running 4-5PSI over the door jam pressure I still am taking an economy hit. It's hard to say for sure because I only drove on my OEM tires for about 500 miles but I think it's about a 10% reduction in efficiency.

When the time comes to replace these (will be several years) I'll be hoping that someone will have made summer tires that are LRR rated (and that the tires are good) but the improved grip (and the increased safety margin that comes with it) is well worth the economy penalty (and it doesn't hurt that I get most of my charging for free).

 

[dbostrom]

Thanks raitchison. I might try replicating that before the weather changes too much; I've got a solid mi/kWh number right now at 2290 miles and if I don't change heating habits there's a chance for comparison.

Any other 'sticky' tire direct experience much appreciated in advance.

 

[thursda]

What summer tires are you riding on?

 

[dbostrom]

Just returned from another 200 mile round trip and I have to say that other than not being able to experience full acceleration from a standing start I'm actually pretty happy w/the tires that came with this car.

To the point of the thread: 44 all the way around, the same as I ended up converging on w/the Volt. Just for grins I tried 36 and the car felt mushy and (strangely enough) less comfortable than at 44.

 

[36 gap]

Tire press
New 2020 at 6000 miles
100 mile daily round trip highway
Averaging 1 psi drop every 2000 miles
On all 4 tires

 

[DAC17]

I have a simple question for the OP. For marketing purposes, we would agree that GM would like to get every mile of EPA-certified range that they can possibly get (currently 259). Aside from rolling resistance, as others have pointed out, there are safety, tire wear and myriad other considerations. If the engineers recommend 38 psi, why do you feel qualified to change that recommendation?