Time For Some New 20" Tires

[ksurfier]

Need to start at 60 PSI then do a test drive for 3-4 miles, then go up to 65 PSI and drive, then go to 70 PSI.... Most likely you will find the sweet spot between mid high 50's and mid to high 60's. If towing or carrying significantly more weight you would air up another ~5-10 PSI..., but doubt that would even be needed...You can completely ignore the other recommended pressures once you go to E rated tire...the minimum pressure for that tire is likely 50 PSI.

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[HaveBlue]

You should inflate to 50 psi because the weight of the vehicle you are mounting them on has not changed from the old tires. Air is what carries the weight from a simple physics perspective. Empty tires at zero psi carry zero weight no matter what is written on the side of it. You can go through the math which is pretty simple. Contact patch in sqin * 50psi *4 tires will give you the carry capacity in pounds. If your GCVW is higher you need more psi. If your tires are only rated at 50 psi you need tires rated to a higher maximum pressure.

The rated contact patch should be available from the manufacturer and is based on the speed rating of the tire. You can run the tire at a lower pressure of course. For instance off road you can run them at 25psi for more traction. The tire still carries the weight because the contact patch has gotten larger. However the speed rating has gone down by a large amount and exceeding it will overheat the tire and it will blow. You can run the tire at a low pressure if the vehicle is lighter or the contact patch is very large due to it being a larger size tire.

 

[Supratachophobia]

Choice is pretty simple.
Want/need 34-inch tires? Keep the same Scorpion AT Tire (275/65R20), the only 275/65R20 under 50 pounds. If range is not an issue then this is the easiest choice.

Is 33-inch and Snow ok? Then 275/60R20 - Continental Terrain Contact H/T (44 pounds) or Kumho CRUGEN HT51 (41 pounds). I would prob. go with the Continental. Might be challenging to find a shop willing to install these if ratings slightly too low.

33-inch and don't care about Snow? 275/60R20 Michelin Defender or the Pirelli AS+ 3 (most reviews slightly favor the AS+ 3). The defender is 2 pounds heavier than the AS+ 3 (but AS+ 3 load rating is 115 instead of 116). If towing is a concern then need the Defender is 116.

Getting the right tire is a different process for each person. If beefy off-road tires are your thing then it's really hard to beat the OEM Scorpion AT. The heavier tires will have more tradeoffs and will drag the range down.

For those pushing the envelope there are the <40 pound tires that will offer the most efficient miles and greater range.

From the cost perspective, tires run $0.05 per mile plus or minus a penny. Someone with a big heavy tire is going to average <2 mi/kw (500 wh/mile), while the middle range will be 2.2-2.4 (420 wh/mile), and a high range will be 2.6 (385 wh/mile) or so. With a $0.25 Kwh, that will be $0.11 plus or minus a penny. So really not much savings to be had either way. Cheap tires with high efficiency (low weight) will cost $1,400 per 10,000 miles while the less efficient and more expensive tires will cost $1,800 per 10,000 miles. With EVs, one of the best approaches is to accept the fact that you'll be lucky to get half the warrantee mileage from a tire and sometimes going with the cheaper tires is better in the long run.

Range wise, heavy tires will be ~250 miles, middle will be as much as 300 miles, and the more efficient tires will get up to ~330 miles (or more).

All things being equal, seems to me the easiest choice is to get the 33" Michelin that Costco sells which is the same as the Defender (Michelin - X LT A/S 2 - 275/60R20). Cost is ~$1,100 and you get the Costco benefits for rotating and maintenance.

Excellent info. What would you say is the absolute best range tire for the price?

 

[ksurfier]

I would not recommend any pressure lower than ~55 PSI for E-rated tire, which works out to a 115.5 load rating. One exception is that the front tire pressure could be a bit lower, maybe 50 PSI on the front (if that is helpful).

Interesting point of view...What is your basis for 50 PSI? Contact patch is total vehicle weight divided by PSI (changes with PSI). What if it's 120 degrees out? Is 50 PSI the correct pressure? Or 10 degrees, 50 psi still good?

This is an E rated tire, the sidewall is equivalent to 10 ply (very very stiff). It's load rating of 3,750 pounds is rated at 80 PSI. Using 50 PSI would bring the tire rating to ~2,680 pounds (load rating of 115). This is borderline and technically below the OEM rating of 116. The tire will likely perform better in the mid to high 50's. A good starting point is 60 PSI and see how it handles.

EVs tend to do very poorly with underinflated tires, I would also not want to risk damage or crashing.

Underinflated tires also generate more heat which destroys the rubber and wears out tread faster.

There's a balance between performance, efficiency, and safety.

Tires should always be tuned for performance and handling (or towing).

Bottom line is the pressure needs to be adjusted for a wide variety of factors in a load E tire, I would target pressures between low 60's (load rating 116 - 2,750 pounds) and high 60's (load rating 120 - 3,000 pounds).

Some may prefer to sacrifice range and efficiency and run lower pressures, I would caution that below high 40s/low 50s could be dangerous.

Here's a very general rule, if a standard tire 120 rating needs load rating of 2,750 then 31 PSI is needed. If an extra load tire 120 rating needs 2,750 then 36 PSI is needed.

Another example (standard load), 116 load can achieve 2750 at 36 PSI. 119 load can achieve 3,000 at 36 PSI. For extra load, 42 PSI achieves 2,750 (116). 42 PSI achieves 3,000 (119). So clearly extra load tires require at least 5-6 PSI additional for same load ratings.

(https://www.falkentire.com/load-inflation)

 

[ksurfier]

Excellent info. What would you say is the absolute best range tire for the price?

Unfortunately the worst price is the OEM AT Scorpion (275/65R20), close to $2,000 for a set (also the heaviest in the below 50 pounds categories). No other 275/65 tires come close to the weight (although 285/60R20 FIRESTONE DESTINATION X/T comes close at 51 pounds).

There's only 1 option below $1,000, the General Grabber 60 HTS (275/60R20), sounds like ~30,000 miles can be expected so it's pretty reasonable...

SCORPION AS PLUS 3 (275/60R20) is 38 pounds and ~$1,000 but is rated 115 (just below the needed 116), I would just stick to 116 and above, wouldn't want to worry about safety or liability of running a slightly lower rated tire, not worth it. It's too bad since it's an 800 A A treadlife and also the highest rated tire by Simpletire. Riviot can talk to this one, something like 2.6 to 2.9 mi/kwh. Also a 70k warranty but not sure it will matter if you can't get them to install it...

If Costco is an option then there is the 70k warranty Michelin - X LT A/S 2 (275/60R20) (Defender - club version). It's about $1,100 and weighs only 40 pounds. Also the highest rating for treadlife (820 B A treadlife). If you look at Tire Rack there are a ton of reviews with large trucks consistently getting >100,000 miles out of a set (Defender LTX). Should do very well on efficiency, likely ~2.5mi/kwh.

 

[Supratachophobia]

Unfortunately the worst price is the OEM AT Scorpion (275/65R20), close to $2,000 for a set (also the heaviest in the below 50 pounds categories). No other 275/65 tires come close to the weight (although 285/60R20 FIRESTONE DESTINATION X/T comes close at 51 pounds).

There's only 1 option below $1,000, the General Grabber 60 HTS (275/60R20), sounds like ~30,000 miles can be expected so it's pretty reasonable...

SCORPION AS PLUS 3 (275/60R20) is 38 pounds and ~$1,000 but is rated 115 (just below the needed 116), I would just stick to 116 and above, wouldn't want to worry about safety or liability of running a slightly lower rated tire, not worth it. It's too bad since it's an 800 A A treadlife and also the highest rated tire by Simpletire. Riviot can talk to this one, something like 2.6 to 2.9 mi/kwh. Also a 70k warranty but not sure it will matter if you can't get them to install it...

If Costco is an option then there is the 70k warranty Michelin - X LT A/S 2 (275/60R20) (Defender - club version). It's about $1,100 and weighs only 40 pounds. Also the highest rating for treadlife (820 B A treadlife). If you look at Tire Rack there are a ton of reviews with large trucks consistently getting >100,000 miles out of a set (Defender LTX). Should do very well on efficiency, likely ~2.5mi/kwh.

Thank you for all that detail. Does it matter less if it's an R1S since that curb weight is less? Also, I *never* plan on towing if that matters. I keep hearing great things about that AS3 so thank you for confirming it. I don't think I'm terribly worried about the 115 rating, should I be?

 

[Supratachophobia]

Unfortunately the worst price is the OEM AT Scorpion (275/65R20), close to $2,000 for a set (also the heaviest in the below 50 pounds categories). No other 275/65 tires come close to the weight (although 285/60R20 FIRESTONE DESTINATION X/T comes close at 51 pounds).

There's only 1 option below $1,000, the General Grabber 60 HTS (275/60R20), sounds like ~30,000 miles can be expected so it's pretty reasonable...

SCORPION AS PLUS 3 (275/60R20) is 38 pounds and ~$1,000 but is rated 115 (just below the needed 116), I would just stick to 116 and above, wouldn't want to worry about safety or liability of running a slightly lower rated tire, not worth it. It's too bad since it's an 800 A A treadlife and also the highest rated tire by Simpletire. Riviot can talk to this one, something like 2.6 to 2.9 mi/kwh. Also a 70k warranty but not sure it will matter if you can't get them to install it...

If Costco is an option then there is the 70k warranty Michelin - X LT A/S 2 (275/60R20) (Defender - club version). It's about $1,100 and weighs only 40 pounds. Also the highest rating for treadlife (820 B A treadlife). If you look at Tire Rack there are a ton of reviews with large trucks consistently getting >100,000 miles out of a set (Defender LTX). Should do very well on efficiency, likely ~2.5mi/kwh.

Also, as long as the tread life is better than 30-40k, I'd just assume decide on range after that. ~$1000 for a set seems reasonable to me. But 2.9m/kw is where I want to live my best life if I can.

 

[ksurfier]

I see too many benefits of the Defenders, it’s the best all road tire. On road the Pirelli’s may perform slightly better. Having a higher load rating makes it an easy call for Defenders, big heavy truck so no need to walk the line… hey Sue 45

 

[Ced]

You should inflate to 50 psi because the weight of the vehicle you are mounting them on has not changed from the old tires. Air is what carries the weight from a simple physics perspective. Empty tires at zero psi carry zero weight no matter what is written on the side of it. You can go through the math which is pretty simple. Contact patch in sqin * 50psi *4 tires will give you the carry capacity in pounds. If your GCVW is higher you need more psi. If your tires are only rated at 50 psi you need tires rated to a higher maximum pressure.

The rated contact patch should be available from the manufacturer and is based on the speed rating of the tire. You can run the tire at a lower pressure of course. For instance off road you can run them at 25psi for more traction. The tire still carries the weight because the contact patch has gotten larger. However the speed rating has gone down by a large amount and exceeding it will overheat the tire and it will blow. You can run the tire at a low pressure if the vehicle is lighter or the contact patch is very large due to it being a larger size tire.

Changed to LT tires (AT Revo 3) and they carry 2475 lbs @ 45psi, which is good enough for the rear GAWR of 4960 lbs (/2= 2480).

 

[ksurfier]

That doesn’t seem quite right, suggest you do the pressure - temp test. Make sure cold is ~46, and hot is 50 or less. If you get more than 4 psi change then your pressure is too low. Move to LT should increase your pressure by at least 5 psi (so 53 - 55 cold would be ideal). Some run the LTs higher to achieve better economy. That tire looks like a great choice at only 51 pounds, would like to see what kind efficiency you are getting. Past 1,000 miles of mixed driving I have 2.36 mi/kWh on the 20” AT Scorpions. Guessing yours will drop slightly (maybe 2.2?).

 

[Ced]

That doesn’t seem quite right, suggest you do the pressure - temp test. Make sure cold is ~46, and hot is 50 or less. If you get more than 4 psi change then your pressure is too low. Move to LT should increase your pressure by at least 5 psi (so 53 - 55 cold would be ideal). Some run the LTs higher to achieve better economy. That tire looks like a great choice at only 51 pounds, would like to see what kind efficiency you are getting. Past 1,000 miles of mixed driving I have 2.36 mi/kWh on the 20” AT Scorpions. Guessing yours will drop slightly (maybe 2.2?).

I get 45 cold / 47 hot. Have some efficiency data I’m working on before/after install. Btw, was able to go back to soft suspension setting with the LT stiffer sidewalls and have nicely controlled handling vs the all-seasons they replaced.

 

[HaveBlue]

I had a few sets of revo tires. Really well made and a serious AT tire. Road manners were good for and aggressive AT. They have a lot of tread and last so will eventually go out of balance. It's worth getting heavy tires rebalanced every 20k-30k or so. Passenger tires don't have that kind of mass and tend to keep bal better. That's independent advice from the Bridgestones themselves. Many tire shops will say it's not needed but you'll notice a big difference again. Worth the little money to do it when you have them rotated.

 

[shamoo]

I have found that my Nitto Recon Grapplers are wearing better than my OEM scorpions ...

What size Nitto Recon Grapplers did you get? I don't see an available 275/65/20.

 

[jjswan33]

What size Nitto Recon Grapplers did you get? I don't see an available 275/65/20.

They have Recon Grapplers either 275/65r20 in a 116T or a LT275/65r20 in an E load range. I have the LT version.

https://www.nittotire.com/light-truck-tires/recon-grappler-all-terrain-light-truck-tire/

https://www.tirerack.com/tires/tire...wcB:G:s&s_kwcid=AL!3756!3!!!!x!!&gclsrc=aw.ds

https://www.tirerack.com/tires/tire...wall Square Block&partnum=765SR0REG&tab=Sizes

 

[ksurfier]

Looks like there may be a LT275/65 at 58 pounds and a 275/60 at 45 pounds … looking forward to driving with a ~40 pound tire to see how it does, the ~50+ pound tires seem like overkill unless you are towing or heavy duty off-road. The low 40’s are the sweet spot for Rivian.

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