15 Silverado 35" Tires and speedo

Dosequis82 · Post by **Dosequis82** » Thu Jan 14, 2016 6:42 pm

Hey guys, I am having a bit of trouble. I have gone from 31 to 38" incrementally and my speedo is always nowhere close to indicated speed on my phone app GPS. My tires are 35s but measure 33 and a heavy quarter/half. The closest I have gotten is 4mph off. Is there a trick to setting these? It seems like it is having no effect.

Post by **mikel** » Fri Jan 15, 2016 10:34 am

have you tried 33.5?

you can fine tune with the metric sizes by adjusting the aspect ratio but .5" increments should be more than enough.

Dosequis82 · Post by **Dosequis82** » Fri Jan 15, 2016 1:06 pm

Is it necessary to also do a TCM install as well? I have just been doing the ECM with adjustable parameters. I can not seem to ever get my speedometer to go over what is actually displayed as well, it is always a speed under actual.

Post by **mikel** » Fri Jan 15, 2016 1:07 pm

No, TCM is not required.

Dosequis82 · Post by **Dosequis82** » Fri Jan 15, 2016 1:14 pm

If I went to an extreme of say 40" tires, I should see a reported speed exceeding that of which I am actually doing, correct? No matter what tire size is selected in measurements of inches, I can not get it to go over, only consistently stay ~4mph slow. I am going to try 315-70r20 and mess with the aspect ratio and see if that has any effect. If I was off by 1 or 2mph I wouldn't care but when it's 5 at 55mph I know I'm gonna end up getting a ticket haha.

15 Silverado 35" Tires and speedo

15 Silverado 35" Tires and speedo

Re: 15 Silverado 35" Tires and speedo

Re: 15 Silverado 35" Tires and speedo

Re: 15 Silverado 35" Tires and speedo

Re: 15 Silverado 35" Tires and speedo