Tire Pressure Help - Mickey Thompson 285/70/17s

Actually it's easy. Light truck tires have LT index and have 3 grades of load capability C, D and E. "E" load tires are heaviest and strongest, capable support a lot of weight, which is overkill for 4Runners but provide a lot of sidewall protection. P, SL, XL tires are passenger tires, they might have different load capability, sometimes at par with LT C load tires, but they have weaker sidewall than LT tires.

Tires should be able to support maximum weight of the vehicle. So you need to look up maximum axle load on a door sticker and divide it by 2 since axle sits on 2 tires. Then you check inflation tables in the Internet for your particular tire and set pressure required to support that weight (required PSI depends on tire size). You can go higher to compensate pressure drop when it gets colder outside or for better tire road contact, but no higher than maximum tire pressure written on tire sidewall. If your tire pressure lower than required to support vehicle weight your tire will be overheating on high speeds and you risk blowing up your tire eventually. LT tires are stronger than passenger tires and can support bigger weight, but they are more sensitive to low pressures, for example for stock size LT tires absolute minimum pressure is 35 psi, but for P/SL/XL tires same size minimum would be 25 psi. So basically LT tires for 4Runners make sense only if you go off-road and need stronger sidewalls for rocks protection.

 

Trying 32PSI today. Seems solid traction so far and not too depressed. Seems like a good pressure for PA.

is there a way to reprogram the PSI range on the 4R to accept a new range?

 

yes, I think I saw it in manual, at lets for 2022 4runners. If I remember it correctly you can set psi or computer will use current psi when you reset the tire pressure monitor from dashboard display.

 

Yes 285/70/17 in the Baja Boss A/T's that you are running.

 

Thanks Musashi! If I remember correct you're also an Elka suspension person, right? Mine are doing amazing. Love them about half dampened. Stay strong!

 

That's me! Love the Elkas, have mine set just below the middle. I'm carrying extra weight in the front with the C4 Lo Pro bumper and winch so I run the fronts a little stiffer on the rebound.

 

Absolutely! My C4 has held up great. Great minds think alike! Stay strong up there!

 

Thanks you too and Happy New Year!

 

Let’s go 2024!!!

 

Have you seen THESE?

 

I thought @raimieb ‘s tires were standard load as well. Last I checked, Mickey Thompson did not make the Baja boss tires in Load C. They either had them as “SUV” tires, or as Light Truck Load E.

As far as I understand, it’s a bad idea to run Standard load tires at high tire pressures, because they are constructed different than LT tires. Only LT category tires the require higher pressures.

Unless I misunderstand, or unless MT state otherwise, I don’t think the tires the OP has are meant to be inflated any higher than is what on the doorjamb.

 

Nice find. I'm going to order these

 

I put them back down to 30. 35 crowns too much and doesn’t wear evenly. Any updates on your end?

 

@Yotaholic
I've been interested in determining exactly what pressure I should be running for decent tire wear @ nearly 2500kg.
Like bassguy said too, with load E's I think the number is 35-38 psi.

 

I tried different numbers and 37 worked best for me. It is super cold 37 though, like early morning 37 lol.

 

I'm still running between 28-30 and I feel like that's where they should be for SL

 

Roger that. Me too!

 

mine are SL which is normal load. Like yours. I reran the psi calculation online and it says 31 for sl load. So you’re on target. Going to try that this morning. Mickey Thompsons site says to cold inflate at that pressure and that it’s fine for them to heat up while driving and be technically over that psi. More damage can occur from under inflation and heat damage than over. So we will see.

 

Keep us updated on how they wear at your pressure. I'm still running the SL 285/70 rugged treks at 28 cold and let them warm up to whatever from there.

I've got about 15k on them now and they seem to be wearing evenly. I have aftermarket screw cap TPMS that also show temp in Celsius and they don't overheat on long trips at 80 mph

 

I probably will be running my 285’s at 35lbs just like my 265’s. Next week sometime my 285’s will be mounted.

 

They really do warm up quite a bit. I started at 31 this morning around 45F. After 20 minutes on the road they were at 33-34. So might go down to 30 cold.

 

Regardless of recommended pressure for SL or Light truck tires, pressure always goes up a few lbs when warmed up. Tire pressure recommendations are given for cold tires.