Your factory tires were 32.1", not 27" diameter, so your 33's are .9" taller. That will throw off the speedometer by approximately 3%. So, if you want your speedometer to be accurate, you will need to re-calibrate. That being said, 3% is not a lot.

 

Yes.
I went to 33" tires and I have a GPS the speedo is off.

 

Assuming your stock tires were 275/55/20 (31.9's), going to a 33" tire will only make your speedo off by about 3.4%.

 

Not to be a dick, but, how would you know the tires were 32.1"? Top pic is new after leveling and the orirginal when I bought em.

With Leveling and Nittos and Fuel wheels

Original wheels and Tires

 

Truck looks great bottom line is you don’t have to worry about fixing the speedo unless 1-3 mph Bothers you that much !

 

Because 275/55/20 is 32.1 tire. This is stock f150 tire

 

I thought it varied, but, never really paid attention I suppose. Thanks.

Someone said 1-3 MPH difference and I noticed that at 70 on the speedo, GPS/Waze said 73. Since I typically set cruise @ 5 over the limit, I will have to careful in 75 mph zones. TX highway patrol gives you 10% variance and 80 might end up costing me ticketed.Thanks all

 

I use this site for tires size comparisons. It even gives you Speedo.

https://www.tacomaworld.com/tirecalc...0r20-285-60r20

yeah spare me I know it’s tacoma site.

 

Because the factory Hankook 275/55-20's are 32.1" tall. That's the only tire offered with the FX4 package on 20" wheels.

Your new tires may look a lot taller because of the wheel offset and aggressiveness, but they are actually pretty close in diameter if they are 33's. What exact size and brand did you buy? Tires vary quite a bit between brands.

Truck looks good by they way

 

Thanx. Nitto Ridge Grapplers 285/60/r20