Low Rolling Resistance Tires

CatDaddy

I'm planning to tow my 320S with my 2023 VW ID.4 AWD electric car. To maximize the range, I am looking at tires with lower rolling resistance than the Rainer Apex ST tires (ST235/75R15) tires that are on the 2022 320S Boondock I'm purchasing. The Rainer Apex tires are off-road tires that probably have a rather high rolling resistance.

Here are a few options I've found:

Greenball Transmaster EV: Only comes in ST225/75R15 or ST235/75R15. I would probably go with the ST225/75R15 which will lower the trailer slightly but reduce the tire weight by ~4lbs each. I've never heard of Greenball tires but apparently Costco sells them.

Goodyear Endurance: ST225/75R15 frequently recommended on this forum.

Hankook Dynapro HT RH12: P235/75R15

Hankook Kinergy PT H737: P235/75R15

Kumho Crugen HT51: LT235/75/R15

Michelin Defender LTX M/S: LT235/75R15 Discount Tire says this size has been discontinued but Michelin says it's available.

Given that the new 320S Boondocks are coming with Goodyear Wrangler Trailrunner SL rated passenger tires, I am thinking that I don't need to get ST or LT rated tires.

The Greenball Transmaster EV tires are the only tires I've found that are specifically designed for EVs and low rolling resistance.  They're also really cheap, but I'm not one to cheap out on tires as I've found you get what you pay for.

Does anybody have any thoughts on this?

manyman297

I went with Hankook Vantra trailer tires. They were made to compete with Goodyear Endurance in terms of specs but obviously much less expensive. We’ve put a few thousand miles on them and they seem great. Link is here: 

https://a.co/d/dQp6nXZ

CatDaddy

manyman297 said:

I went with Hankook Vantra trailer tires. They were made to compete with Goodyear Endurance in terms of specs but obviously much less expensive. We’ve put a few thousand miles on them and they seem great. Link is here: 

https://a.co/d/dQp6nXZ

Thanks, I didn't see that option in my search. Did you notice any improvement on your gas mileage after you switched? I'm trying to find tires with lower rolling resistance.

MuttonChops

EV designed tires are very 'hard' to handle the high loads and braking stress . . . not needed on trailer, any street thread (not A/T) with the correct load rating and extra strong side walls [ST or LT type] will have lower rolling resistance than the 'stock A/T' tire and softer ride then an EV tire.

That said would be surprised if trailer tire impacts Miles per Charge more than a small bit when compared to the large impact of trailer weight wind resistance. 

manyman297

@CatDaddy Not really if I’m being honest. The biggest issue with our 400 is just the shape of it and the turbulence caused between the truck bed and front of the camper. 

But the tires seem fine so far. Time will tell. We don’t put a ton of miles on our camper so the endurance seemed like overkill.

Mickerly

You may want to look at Carlisle tires. I think they distribute through SAMS. There are a great highway trailer tire.

I went with Hercules Strong Guard ST (Hercules is a division of Cooper Tires). They are load range D, so I run them at 58psi to give them a little flex. You will have to find a place that caters to the agricultural community to find Hercules.

Have the installer balance the tires. Yes, this is not typical for trailer tires. It makes a significant difference. 

Slackers

We purchased our Carlisle tires through Walmart online. We had them delivered to our local store. For an additional fee they were mounted and balanced on our rims. We've had no problems through more than 7500 miles they've been on our Tab.

Sharon_is_SAM

We replaced our tires with Carlisle’s on our CSS.  No problems.

rfuss928

Some info from and a link to a Consumer Reports article on the subject...


https://www.consumerreports.org/cars/tires/low-rolling-resistance-tires-can-save-you-money-at-pump-a1547901110/

CatDaddy

rfuss928 said:

Some info from and a link to a Consumer Reports article on the subject...

I looked at that review CR did. Unfortunately, most of those tires are not available in the size I need. I appreciate the help!

CatDaddy

MuttonChops said:

EV designed tires are very 'hard' to handle the high loads and braking stress . . . not needed on trailer, any street thread (not A/T) with the correct load rating and extra strong side walls [ST or LT type] will have lower rolling resistance than the 'stock A/T' tire and softer ride then an EV tire.

That said would be surprised if trailer tire impacts Miles per Charge more than a small bit when compared to the large impact of trailer weight wind resistance. 

The tires on both of my EVs ride better than the tires I had on my 2005 Altima back in the day, but I agree that EV tires are designed to handle heavier loads associated with EVs.

The Greenball Transmaster EV tires are ST rated with load rating of E which is going to really stiff; even stiffer than the D rated Rainer Apex tires currently on the trailer.

I'm on the fence about whether I really need ST or LT rated tires. The current 320S Boondocks are coming with Goodyear Wrangler Trailrunner AT tires which appear to be standard passenger tires. They are SL (Standard Load) tires with a load index of 105S. I'm not a tire expert, but they are rated as if they're standard passenger tires.  For this reason, I am skeptical of the need for ST or LT rated tires.  I'm always open to be being educated.

I agree that the lower rolling resistance tires will not have a huge impact on range. Some of the tire tests I've read suggest that getting a 10% increase is about the maximum.  I think the rolling resistance of the Rainer Apex off-road tires is probably quite high compared to a highway tire, so maybe I could get 5-8% more range? That's a complete guess. Part of me wants to try the Greenball Transmaster EV tires just to find out. They are less than $100 each so the experiment wouldn't be crazy expensive.

manyman297

My understanding is that ST rated tires tend to be E load range not so much for travel but for when the camper is parked. The thicker sidewall provides more support and less sidewall flex. For a small camper Iike the 320 I think load index is less a factor since any SL tire should be able to handle the weight. 

d_v

I went with both a smaller trailer tire and wheel. Lower rolling resistance, less weight, lower camper height. I wish I had a good A/B test on consumption difference but I don’t. With the smaller ones I’m getting 620ish wh/mi at 53mph towing with a Model Y.

Tires are ST205/75/14 Goodyear endurance, load D.  

CatDaddy

d_v said:

With the smaller ones I’m getting 620ish wh/mi at 53mph towing with a Model Y.

I just got home from picking up my new to me 2022 TAB 320S Boondock in Medford, Oregon. I towed it up I-5 today. I'm still compiling my data, but it looks like I averaged something like 555 wh/mile on the trip. A bit more in the hills and a bit less on the flats. The trailer has ST235/75/R15 Load D Rainer Apex tires. My TV is a 2023 VW ID.4 AWD.

I was surprised to find that speed didn't make much difference, but the hills really did. I'm wondering if I need to tweek the settings on my brake controller.

SLJ

Get a smaller tire. It will reduce the T@Bs height and put more of the TAB's front surface area behind the tow vehicle. That will make more of a difference in gas mileage than a tires rolling resistance. It's all about surface area once you're up to highway speed. Hills and weight are the other consideration.

ColleenD2

Tire question while I have you all. I am having my Goodyear endurance put on the camper today but I'm curious about tire pressure. Do we follow the pressure on the tire? Of course on the label of the tab it says 50 but that's because they expect the Chinese tires that are on there. The endurance says 80. I want to be safe.

SLJ

ColleenD2 said:

Tire question while I have you all. I am having my Goodyear endurance put on the camper today but I'm curious about tire pressure. Do we follow the pressure on the tire? Of course on the label of the tab it says 50 but that's because they expect the Chinese tires that are on there. The endurance says 80. I want to be safe.

To do it correctly you need to weigh the tires/axle when hooked up (can do it on a CAT scale at a truck stop) and then divide the axle weight by 2 to get the weight of the load on each tire. Then go to Goodyear's web site and check the chart for that tire/size. It will tell you the required pressure for your weight. The label on the T@B is only for the original tires from the factory.

CatDaddy

SLJ said:

Get a smaller tire. It will reduce the T@Bs height and put more of the TAB's front surface area behind the tow vehicle. That will make more of a difference in gas mileage than a tires rolling resistance. It's all about surface area once you're up to highway speed. Hills and weight are the other consideration.

The data suggests that wind resistance isn't as strong a factor in range as I thought. When going 65 mph on the highway, I was getting about 1.8 miles/kWh with the trailer.  Dropping it to 60 mph dropped the power consumption to 1.9 miles/kWh.  I was getting about 2.0 to 2.1 miles/kWh around town at 35-40 mph.

Without the trailer, I was getting around 3.3 miles/kWh on the highway.  

This suggests to me, that speed isn't as big a factor as I thought, which means that lowering the trailer probably won't help that much with range, but will definitely impact the ground clearance.

I'm not sure that lower rolling resistance tires will help that much either, which is why I was asking if anybody had any data about it. I wish tire manufacturers published rolling resistance information for all of their tires.

Horigan

ColleenD2 said:

Tire question while I have you all. I am having my Goodyear endurance put on the camper today but I'm curious about tire pressure. Do we follow the pressure on the tire? Of course on the label of the tab it says 50 but that's because they expect the Chinese tires that are on there. The endurance says 80. I want to be safe.

You can run at the max operating pressure of the tire, which will reduce rolling resistance.  Whether you'd be able to measure it is an open question.  However, running at max pressure does impose a harsher ride for the trailer, so you may experience more vibration related failures over time.  Tires have a pressure vs. load curve, hence the suggestion above to weigh the trailer to determine the load.

dlb

Lower pressure in a tire allows it to flex more, softer ride, more heat build up in the side wall, bad for the tire life and increased blow out potential.  I buy the tire I want for the specific vehicle and run them at maximum tire pressure recommended by the tire manufacturer.  If you don’t want to run with 75-80 psi, buy a different tire.

Binghi

No way I’m going to inflate my Goodyear Endurance tires to 80 psi. They run fine at 50 psi and I’m not going to rattle and jar my trailer into oblivion. I’ve never inflated a tire to 80 psi and likely never will.

manyman297

I have E-rated tires and run them at 75-80psi and they seem to ride well at that pressure. When parked there is minimal sag in the sidewall.