Just had the 513s installed, shop said that the speedo would be 10% FASTER now, was about 6-8% SLOWER after just the tires. This doesnt make sense to me, I clocked the speedo on the way home w/ another car and it was right on. Also noticed that the DIC was turning out some pretty crappy milage #s on the drive home. Whats the deal??

 

You must have had a break in communication.

No doubt you will be travelling faster than the speedo says.

 

After my 5.13's and 35's my speedo read 7 mph lower and the fuel economy readout was way off. The hypertech speedo calibrator fixed things.

 

Does the hypertech adjust for both tire AND gear sizes and what about shifting points- thx

 

Yes, very true, to be 7 MPH off you would have to be going around 70-75 MPH. When I'm travelling actual speed of 65-66, my speedo is reading about 60 MPH. That is based on looking at my Garmin Trail Guide speedo readout which seems pretty accurate.

 

around town you will be going 4-5 MPH over what your speedo is saying

 

Yup, when I mentioned 7 mph low I should have said that it was at 75mph. So that would mean 9-10% low.

As to the shift points being changed the answer is that it now shifts as it did when it was stock. The shift points are off with just tires and/or gears because the computer has bum information as to your speed. The shift points return to normal because now the computer is basing it's decsisions on your actual speed. My wife really noticed the difference.

 

How do your 35's actually measure out on the ground? My 35" ProComps measure out to 33.5". If I had 4.88 gears I would be at the same RPM as someone with acutal 35's with 5.13 gears! I have been trying to decide which gears to go with 4.88 or 5.13.

 

Do a search on gear choice.....then buy 5.13's!!

 

I have 34's and as soon as Ed has time (hopefully very soon), I will have my 5.13 installed. Don't fear the gear.