[devinthorpe]

I've read much of the discussion about terrain scores here. I'm an experienced EV driver and have had my Bolt for 3 years and 50,000 miles.

I recently got new tires. After having them installed, I started getting bad terrain scores. It's like the car thinks I'm towing a small trailer (which I regularly do, but not with the new tires).

I realize tires have an impact but I chose the tires for efficiency. I cannot feel any difference in handling at all. Feels fine.

Is there anything the tire guys could have done to the car to cause the bad terrain scores?

 

[Plaj]

Which tires did you buy? Pretty much everything on the market is less efficient than the stock Michelin Energy Saver tires, unfortunately.

 

[devinthorpe]

Let's assume for this conversation that the problem isn't the tires.

(I got Continental ExtremeContact DWS 06 Plus but was not replacing original tires.)

Please help me think of what else could have happened. The guys who put on the tires were careless, didn't inflate any of them correctly and I had to go back to them to have them rebalance the tires because of a wicked vibration. Now it feels fine, but that big bad terrain score makes no sense to me. I worry that they sabotaged my car or stupidly hurt it.

 

[Plaj]

I do not think there is something the tire shop would have/could have done that would make your car less efficient. Sounds like you now have the tires properly inflated, so it isn't that. The change in tires was my first thought because that's the main thing that has changed. New tires are also a little higher rolling resistance than worn tires, even of identical type.

 

[usedBolt]

If you didn't get Low Rolling Resistance tires, "correct inflation" might actually be a bit overinflated. That's possibly for load capacity, but mainly to make them harder for rolling resistance reasons. Also, even if you want to just use the officially correct pressures, check; too many shops just set them all at 32 and ship it out (Bolt specs 38 all around). Had that problem with the Toyota dealer and the Prius.

 

[Sean Nelson]

...I started getting bad terrain scores.

You're not driving in the wrong direction on roads designed like this, are you?

Is there anything the tire guys could have done to the car to cause the bad terrain scores?

I suppose if they screwed around with the wheel alignment badly enough the tires could be scrubbing the pavement and causing extra friction. Normally I'd think this to be highly unlikely, but if they couldn't even get the tire pressure and balancing right then perhaps it's possible.

 

[devinthorpe]

You're not driving in the wrong direction on roads designed like this, are you?
View attachment 51141


I suppose if they screwed around with the wheel alignment badly enough the tires could be scrubbing the pavement and causing extra friction. Normally I'd think this to be highly unlikely, but if they couldn't even get the tire pressure and balancing right then perhaps it's possible.

Good thinking. I don't feel any pulling or tugging or anything else to suggest an alignment problem. Do you think I could have a big problem with the alignment that I wouldn't feel?

 

[Sean Nelson]

Good thinking. I don't feel any pulling or tugging or anything else to suggest an alignment problem. Do you think I could have a big problem with the alignment that I wouldn't feel?

I have no idea, but it there really is some sort of rolling resistance issue related to the tire change it seems like a plausible bet.

Of course there are also other possibilities. For example, if you've just entered the rainy or snowy season then driving on wet or snowy roads would require more power.

 

[drdiesel1]

It takes on average of about 300 miles for tires to break-in!

 

[Electric Idiot]

Sometimes I wonder why they put terrain on there. It's not like you can change the road.

Like Climate makes sense because you have the choice of freezing your ass off or heat.

And battery conditioning. I would be alarmed if the battery was a passive device.

 

[Sean Nelson]

Sometimes I wonder why they put terrain on there. It's not like you can change the road.

I think the intent is for this screen to try to explain why you're getting better or poorer efficiency (i.e., range). If your range tanks and the terrain graph shows "-5", that probably has a lot to do with it. Sure, it may be out of your control, but if it stops just one person from coming to this forum and complaining that their range suddenly dropped for no apparent reason, then it's worth it for all of us!

 

[usedBolt]

I think the intent is for this screen to try to explain why you're getting better or poorer efficiency (i.e., range). If your range tanks and the terrain graph shows "-5", that probably has a lot to do with it. Sure, it may be out of your control, but if it stops just one person from coming to this forum and complaining that their range suddenly dropped for no apparent reason, then it's worth it for all of us!

Extreme example: took a little day trip last fall to see the colors in the Sierra (and have lunch at a favorite lake). Started at about 300' altitude with the a/c running. Ended up near Carson Pass at about 8500' elevation with the heat running. Efficiency per the DIC on the way up was just over 2.5 miles/kwh. On the way back, it got up to almost 8 with all the regen going down 88 to Jackson! Settled at about 4 for the round trip. And there are EVGo chargers at the Raley's in Pollock Pines for a short bonus shot halfway up (at the end of the freeway running) while grabbing a few picnic supplies.

The "terrain" rating was a solid -5 at Pollock Pines, but was edging into positive territory by Jackson on the way home.

Since I usually do short trips, and the place has lots of hills, "terrain" is almost always negative for me.

Edit: other ones like that are battery conditioning and climate control. Those can never be positive; all they are really is a reason for your poor energy efficiency, not something you can easily control. At best, they're both zero. You can, of course, reduce the climate control penalty by turning off the heat or a/c, but that's often just not feasible (when it's <freezing out, or >100F). So that's all information, but the only thing you can really control is driving style - which does help.

 

[devinthorpe]

I have no idea, but it there really is some sort of rolling resistance issue related to the tire change it seems like a plausible bet.

Of course there are also other possibilities. For example, if you've just entered the rainy or snowy season then driving on wet or snowy roads would require more power.

Good thinking, but no. The opposite. Just entered the dry season.

 

[redpoint5]

I don’t know what “terrain” means in your context. That said, new tires always cause a noticeable efficiency hit.

 

[devinthorpe]

The Bolt provides a Terrain measurement in the energy information data as feedback for understanding what impacts your range.

 

[GJS_MA]

Just to cover the obvious: did you check that they installed the right tire size? Larger tire diameter (or significant over-inflation) could affect odometer measurements and derived calculations. Comparing speedometer and odometer readings with corresponding GPS speed and distance over a trip could show you if there's a significant calibration issue.

Rolling resistance could be a factor with these tires. A review at Continental ExtremeContact DWS 06 PLUS reports losing 10% in fuel range and mpg after switching from Michelin Pilot Sport AS3's.

 

[MichBolt]

It might still be worth checking the alignment. There can be alignment problems that don't show up with a pull to either side, like too much toe in or toe out.

 

[devinthorpe]

Just to cover the obvious: did you check that they installed the right tire size? Larger tire diameter (or significant over-inflation) could affect odometer measurements and derived calculations. Comparing speedometer and odometer readings with corresponding GPS speed and distance over a trip could show you if there's a significant calibration issue.

Rolling resistance could be a factor with these tires. A review at Continental ExtremeContact DWS 06 PLUS reports losing 10% in fuel range and mpg after switching from Michelin Pilot Sport AS3's.

What a great and helpful response! Thank you so much! I'll check it all out!

 

[devinthorpe]

It might still be worth checking the alignment. There can be alignment problems that don't show up with a pull to either side, like too much toe in or toe out.

That's interesting. I hadn't fully considered that possibility. I've wanted to avoid the cost of an alignment but it seems to make sense now.

 

[efbolt]

Maybe the terrain score is overly sensitive. Mine took a hit when I got new tires, but my miles per kwh isn't bad.