Hi. I know it has been posted here before, BUT since I can't effectively search the forums, I'll just ask it again...
I have replaced my stock tires on my 1998 F150 with 285/75/r16 and was wondering which speedo gear to get, and where can I get one?
I have a 3.55 rear end, and the original tires were 255/70/r16.
Thanks.

 

They are very close in height as the 265/70/17 that come on the off Road package. I ordered a speedometer gear for that application from the Ford dealer ship. You can go into the following website to compare sizes: www.eunos.com/tirecalc/
Also Superlift has a speedometer calibrator called TRUSPEED. They did not have an application for my 99 2000 4X2.

 

You have a 19 tooth now with the 30.1's. You need a 17 tooth to get as close as you can to stock, I can gaurantee a almost exact reading with this gear. I'm sure your gear's teeth run to the right, but remove it to make sure your getting the same style gear as stock, or it's not going to fit. But a 17 tooth should fix you up.

-Kelly

 

You should verify what gear you have in there now (stock). Mine was the same basic setup. 3.55, 255/70/16 tires, 5.4, e4od tranny and mine had a 20 tooth gear in it. I put 265/75/16's on it, which are the same height as a 265/70/17 (which came on the ORP optioned rigs). I put in a 19 tooth gear to bring my speedo/odo back to normal.

I think Whiplash_F150 has it right in that you'll need to drop 2 teeth from whatever gear you have in there now. Maybe the 4r70 tranny uses a 19 tooth stock gear????

Just thowing it out there because I did have the 20 myself....

 

Thanks for your help guys. This weekend I'll crawl under there and check it out.

 

I went to install the gear & come to find out it is electronic.
I have to go to the dealership & have it reprogrammed.
(99 & up have electronic speedo gears)