DodgeTalk Forum banner

Status
Not open for further replies.
1 - 18 of 18 Posts

·
Registered
Joined
·
333 Posts
Discussion Starter #1
Hey...I am about to get new tires for my truck and am planning on getting 285/75/16s. My question is.....what do I do to adjust the speedometer so it reads correct? I am going to take the truck into the dealership to have it aligned after the tires and was just wondering if that is the time to have dealer correct that? Can it be done? ...and how much does it cost.

Also can a hypertech programmer and superchips correct that too, because I might look into that sometime down the road?

Thanks for any help!
 

·
Registered
Joined
·
332 Posts
Look on www.tirerack.com and get the revs/mile for your tire. This is what the dealer will need to adjust the speedo. I don't know what the cost is. If you use the hypertech, you need to tire diameter which I believe is also on tirerack.
 

·
BLACK
Joined
·
1,343 Posts
I used my hypertech to correct my speedo. Was pretty easy and worked well. Now my speedo is dead on in comparison to the mile markers on the side of the highway.
 

·
Registered
Joined
·
132 Posts
My truck had 285s on it when I bought it. I got pulled over twice clocked at 71 in a 65 when I had my cruise set on 65. I also measured it by the highway mileage signs. I registered 14.4 miles for every 16 miles I had driven. I have 265s now and haven't been pulled over yet.
 

·
Registered
Joined
·
1,264 Posts
With 315/75/16's my speedo and odometer are 18% low. When my speedo says im doing 65 I am really doing 77. I used some little flash program that takes stock tire size and compares them to the new tires. I don't remember where I found this but it was accurate, I calculated myself by using mile markers that my odometer was off by ~15%. If i find it again I'll post it here.
 

·
Registered
Joined
·
5 Posts
Late response but, I have 285 75 16's on my 97 3/4 ton and have gone through numerous radar checks (the radar trailers they put on the side of the road to tell you how bad you are speeding without giving you a ticket) and my speedo is always right on with the radar.
 

·
Registered
Joined
·
233 Posts
I have 285/75s and I think mine are off by 2.5 mph or so. When my speedo says 65 I'm really doing 67.5 or so.
 

·
Registered
Joined
·
157 Posts
Don't worry about it. You're not off by much.
 

·
Registered
Joined
·
85 Posts
Before I changed my speedometer with the programmer Mine was off by 6 mph with 285's. Now it is dead on. Still took a little fine tuning with the programmer.
 

·
Mmmmmmmmm, beer.
Joined
·
2,485 Posts
Usually 285's will put you off by 5-6 mpg. That is enough to make it worth correctingin my opinion. Not only does it impact your speedometer, but also you odometer and calculations you make to determine your gas mileage.
 

·
Registered
Joined
·
333 Posts
Discussion Starter #12
Ok...Thanks everyone.....Will the programmer be just as accurate as if the dealer adjusted it??
 

·
Mmmmmmmmm, beer.
Joined
·
2,485 Posts
Should be, the dealer changes the same PCM setting that the programmer changes. I used my Hypertech to adjust mine.
 

·
Registered
Joined
·
104 Posts
.
Put 285's on our '98, and did just that... the dealership adjusted the pinion thingy to make the speedo read correct. Works great. Also had the shift points tweeked.

.
 

·
Registered
Joined
·
27,633 Posts
I have 265x75x16 tires on mine and 72 MPH on the speedometer was what the policeman wrote on the first ticket I had gotten in over 15 years said 2 years ago.
 

·
Registered
Joined
·
29 Posts
Hypertech for V10

Does anyone know if they make a programmer for a V10 or if I can use one of the others.
 

·
Registered
Joined
·
85 Posts
no programmer that i could find. altough jet makes a plug in that's unadjustable. The only other way go go with the speedo is a specific programmer that they make just for the tranny. It wires into the tailshaft, and you can adjust it to any tire or gear change that you make.
 

·
Registered
Joined
·
29 Posts
Thanks, that's good info. I'll try that.
 
1 - 18 of 18 Posts
Status
Not open for further replies.
Top