Hey guys, I just received my 33's yesterday. I wanted to put them on now but I know that it'll change the speedo and everything. But my main question is, I can't get it -reflashed until monday so what do I do? Can I put them on now and if I do, what is the difference I'm going to see??? Please let me know ASAP. thank you

BTW, currently, I'm running 17's with Factory 32" tires. The tires I got are 33's on 16" wheels.

 

I calculated 2.6mph off when going 65mph, so its probably not a big deal

 

The biggest size they're gonna be able to flash ya for is 32", so if you have 32's now, there's no sense in having it done again. I went from the 30ish" stockers up to 33" and haven't had it reflashed yet and haven't had any probs. Yeah, the speedo's off a bit, but I'm not going to go outta my way to have it reflashed just so it's a little less inaccurate that it is now.

 

Go with the flow of traffic. My CJ has 38s and after installing the chevy drivetrain I never installed an electric speedo (CJs were cable driven) so I haven't had a speedo since the rebuild. Granted, the CJ isn't on the road much.

 

You're only 1/2 an inch off, so it shouldn't matter much. It doesn't on mine.

 

Actually, I'm only 1/2" lifted by the tires but still is 1" more in diameter. But yes, I drove it after I put them on, on Saturday. Test drove behind my friend's car and it's about 1-3 miles off depending on speed. So it's not a big deal anymore. Thanks for your answers guys. I'll post pics up on "show your 33s" today.

 

I went from the stock girlie 30 inch tires to 33 inch BFG MT. I have 4.10 gears and my speedo and Odo is slow exactly 14% as measured by GPS.

that's 14% at any speed.

Don't worry about anything else, in fact I figure my odometer will always have 14% less miles than actually driven.

 

If you know the exact measurements of the tire's diameter you can calculate the percent change. Example from above: (33-30)/30 = 10% change

You can now multiply your speed by that.

 

I have 33x12.5 on the JK and they haven't changed the speedo at all (or not in a way thats perceptible to the human eye) so I don't think there's a need for re-flash.

 

Well you don't know the exact diameter of any tire. Just because it says 33 does not mean exactly 33 inches. If this were true, then my GPS measurement, measured over a few hundred miles is off?

Most 35 inch tires are spec'd out at 34.5 or 34.8 inches, and each manufacturer is different.