Questions following new tire installation - 40 PSI??

After much deliberation (Google and YouTube) I finally purchased a set of Goodyear Wrangler DuraTrac tires for my 2020 ACOR. I opted for the slightly narrower LT245/75R16 120/116 E rather than the stock 265/70R16.

1. The shop that installed them set the pressure to 40 PSI though, rather than the 30 PSI stated on the door sticker. Do they know something I don't? I didn't think pressure would be different for a different tire. They otherwise seemed competent, but I'm not generous enough to give them a pass on this one. I actually sort of like the harder ride on the surface roads, but I'm thinking to set it back to 30 PSI unless I can get some evidence for something else.

2. I'm not a lead foot, and generally avoid jack rabbit starts. However, my first takeoff from a stop sign on wet asphalt after leaving the shop resulted in quite a bit more wheel spin than I saw with my previous worn OEM tires. Are tires more slippery when new? Will this likely improve? Is it perhaps related to the (over)inflation pressure above?

3. It's been a while since the days when I turned wrenches for a living - before TPMS was the norm. The shop charged me for rubber valve stems, but aren't those integral to the TPMS sensor? Do they actually get replaced still?

Your thoughtful responses are much appreciated!

 

Would definitely stick to the door jam recommended pressure, that allows better control, proper ride and performance. If the tires are the same size should be good to go with factory pressure. Anything higher has marginal gains on fuel economy at the cost of ride benefit and handling

 

They scammed you on the valve stems, the Tpms valves are one piece, they wouldn’t have to touch them to swap tires.
I run 30 in the back with a leer canopy and 35 in the front.

 

Thanks. I'll be questioning them about this when I return for a re-torque.

 

So it seems they may know something I don't know about tire pressures and conversion to different tire sizes/ratings...

I've learned just enough to hurt myself, but have a look here and read the paragraphs below the calculator before commenting: The results are as follows:



Now, I gather this means that the pressure needs to be increased to maintain the rated load capacity. I haven't really looked at what that is for a Tacoma and how much of that I'll actually be needing (I'm not hauling anything heavy), but if I'm understanding this correctly then running these new tires at 30 PSI gives a lower load rating than the OEM setup.

 

BFG actually told us to start setting the E's at 44psi or they won't qualify for warranty (Not that any tire ever does)

I set E's to 40psi on customers trucks, it's for liability.

It's not ideal, but its for the load rating.

 

Do you know if there's a way to determine the optimal tire pressure? I'm talking about general on-road use here. Offroad is a different story, and I'll be airing down as needed.

I'm concerned that having a higher pressure with lower loads might give me a smaller contact patch and cause the tire to wear more in the center.

 

If unloaded, 30psi is fine for cold pressure. If towing or hauling, bump up to 40psi.

Ultimately E rated tires are not designed for light trucks, so you'll never get proper edge wear.

I bumped mine up to 44psi when the gas prices were bonkers a year ago.

 

Thanks. I have no idea of your qualifications, but you sound convincing. ;-) I know that the door sticker is there to make things easy for people who don't know any better. I've always gone that route for "safety", but I'm beginning to see that this is something that can be altered within a range for certain conditions.

I went with the 10-ply because of my perception that they will offer more protection against puncture on sharp stones and maybe other hazards. I'm committed now, so if I'm wrong on this gently let me know and I won't make the same mistake next time.

 

Just a quick update for #2... I'm not sure about the wet road thing, but OMG on greasy snow covered roads these things are more impressive than I'd have imagined!

I have to get some hours on them, but so far I'm very impressed. Granted, just about anything would have been an improvement over what they're replacing.

 

I just put 37 PSI all around. Never had a problem in 11 years.

They wear nicely. Get a good tire gauge, not those "pencil" things.

Similar to what I have:

 

Set them to the recommendation on the door sticker. If decide to tow or load the bed with weight increase the tire pressure as needed. It’s really not that hard.

 

I live at 6,500 ft elevation and both the dealership and Discount Tire set my tires at 40 psi. They say it is to compensate for the elevation.

 

@Pinatacoma tires to grip better after they've been "scrubbed in" a bit. As far as the valve stems, unless your 20 is different than my 2022 the sensors are attached to the back of the rubber stems with a small screw. I removed mine and IIRC it was a small torx but. It's quite standard for places that do tires to keep the new style rubber stems with the threaded insert on the back in stock nowadays. They look very similar to the ones on the left in this picture.

 

The door sticker is for stock SL rated tire pressure, not an LT tire which needs a higher psi.

 

Mine definitely look like the one on the right (from the outside, anyway). I'm very doubtful they were replaced.

 

Stick with what that PSI calculator has told you! LT tires need higher psi over SL rated. Just because some people run lower pressure, doesn't mean you/they should! At 30psi (vs 42psi), you are running those tires 28.6% lower pressure than recommended.

I recently went through the exact same thing as you. Got LT tires for the deeper tread depth. Leaving the shop, I thought my kidney was going to explode from the harsh ride. Shop set my tires at 45psi. I now run 40psi all round based on that psi calculator.

 

If they were the metal ones then they probably weren't replaced. My point was if they are the rubber ones it's very possible they were.

 

@Haole Toy, thanks for the recognition, we are glad your local Discount Tire store was able to get you taken care of.

 

The Show Low, AZ. store is great.