baddceo

I am about 10 days into my level kit and new rims and tires 20x9 33x12.5 Open Country ATII. I didn't reset my avg MPG but have been watching it go down from 17.4 to now 17.2. I can tell it's probably going to level out around 16.8 but it's interesting that my in city mileage is actually better than my highway mileage. Figured I would see a reduction but not a reversal. Anyone else notice this? I guess drag and rolling resistance is more impactful under higher speeds. I missed that session in physics.

On a side note these tires are quite loud on the highway. I hope I am still going through a bit of break in period and hope they my quiet down some but damn they sing. DB rating prior to new tires was 69 at 70mph. The same stretch with new rubber is 76 to 77db. That's a big jump and if you are trying to understand how much louder that is you can use a db meter from the app store or sit in your living room with the TV on set to 69db and then 76db. Maybe it's more noticeable to me because I knew how it was stock...

While I don't really care that much I spend very little time on the highway I also wasn't expecting a 7db-8db increase in cabin noise. The things you do/tolerate for a little eye catching change.

Scott91370

It's actually going to be off quite a bit more if you have not reset your speedometer to the new tire size.

marshallr

The speedometer and odometer are now off by about 7-8% and the trucks computer is basing the fuel mileage readings on the old tire diameter. It changes your axle ratio also

Plug in the numbers for your old and new tires here and you can get real numbers for your truck

https://tiresize.com/comparison/

baddceo

My stock tire size was 275/45/22 so all the research I had done prior indicates about a 4% difference. I am going to go ahead and get FORScan to make the changes. I know nothing about axle ratio. Will changing the tire size or effectively the new diameter setting in FORScan adjust the axle ratio as well?

Thanks

Scott91370

Adjusting the tire size in Forscan is all you need. Axle ratio does not matter.

Kingofwylietx

That is a big increase in sound. My experience with all terrain tires is that they start by having a certain amount of road noise...and very slowly get louder over time.

baddceo

Yeah and I was hoping that they would quite down after an initial break in. Not sure what to do. I have another 250-300 miles before I need to make a decision under the try and buy option. There aren't a ton of other choices out there that I love in the 33x12.5.20 size. I'd even consider a more highway tire and may have to consider a 305/50/20 or something else to get there without losing the stance I spent weeks researching to get.. Ha. Any tire options you guys want to throw out in a highway would be great. I really want to be in the 305 range.