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+--- Thread: Tires (/showthread.php?tid=6700)
Tires - EmJay - 08-25-2015
OK so I've had some time to put my new car on the highway. Boy do I understand the desire for another gear on these 722.3 ATXs! S, in lieu of finding a 722.5 or 722.6 for my 30 year old sedan, I was wondering 2 things.
#1 what are thoughts of running a larger tire? Currently with stock size 195/65/14. Was considering some 205 or 215s to give myself an extra inch or 2 in diameter.
#2 if I do such, how does one adjust the speedo? IM used to swapping speedo gears on the transmission.
RE: Tires - Keino - 08-25-2015
No need to adjust your speedometer??
If you switch from your current setup to 205/65 14 the tires rollingcircuit(?) not sure of the proper word, will be 2,13% higher, 215/65 14 will be 4,27% higher.
Atleast in Sweden you are allowed to change this up to 5% from original size tires.
Dunno about the U.S however
RE: Tires - EmJay - 08-25-2015
I'd like to have a correct speedometer, as future interstate travel is planned. No laws in my area about changing tire size
RE: Tires - Keino - 08-25-2015
(08-25-2015, 11:03 AM)EmJay I'd like to have a correct speedometer, as future interstate travel is planned. No laws in my area about changing tire size
Hehe
Well then I can't help you. I once had my speedo recalibrated, but sent it away to be done by a professional. Maybe someone else knows how to diy?
RE: Tires - Greazzer - 08-25-2015
Yup ... Mine is way way off too with the 2:65 LSD differential and I just added 15" tires. I am going to re-calibrate my face plate on the speedo once I get the engine installed. No way to get a precise speedo cluster if you start changing tires, changing differential gearing, et cet. The customer made plates are cheap and look factory.
RE: Tires - EmJay - 08-25-2015
Hmm, so not as simple as swapping speedo gears. Rats. Ah well, my truck still has an inaccurate speedo so what's one more 300K vehicle with a slow speedo?
RE: Tires - EmJay - 08-26-2015
So no other thoughts about a larger tire?
RE: Tires - raysorenson - 08-26-2015
In my experience, the old speedos are very optimistic. Have you checked it against GPS? There's likely room increase tire diameter and improve speedo accuracy.
As far as adjusting, I think you can adjust the distance from the cup to the magnet.
RE: Tires - EmJay - 08-26-2015
My speedo already reads slow. 75=72GPS
RE: Tires - raysorenson - 08-26-2015
You're saying an indicated 75mph when you're really doing 72 is reading "slow"?
RE: Tires - EmJay - 08-26-2015
Err, I'm going slower than stated. Sorry for confusion. But yes, larger tire may help that. Thanks!
RE: Tires - MFSuper90 - 08-26-2015
I'm running 215/55r16 if I remember correctly. Slightly larger than stock, and it actually did help drop my rpm a shade.
I think the extra weight of the tire kind of negates the effects of fuel economy. But then again I went to a heavier rim as well
RE: Tires - swampmonkey - 08-27-2015
larger tires makes a difference, but not much, i run 195/70r15 in the back of my w123, and had the same on my 240d w115 with a 3.07 differential.
you are talking about your 1985 300d w123 right? how about fitting a 3.07 from a 300tdt aswell as the speedometer, works good on two 72hp 240d manuals i have. (one with a 2.88 and one with a 3.07) so should work without a problem on your automatic 300d 88hp car
that way you will get deacent rpm, and cruising at 60mph is acctualy a pleasure.
RE: Tires - EmJay - 08-27-2015
I thought my 85 had a 2.88 rear? Why would I want a higher gear to lower my RPMs?
RE: Tires - Petar - 08-27-2015
He thought that you have a non turbo 300D
Keep you diff. Or maybe go with a 2.47 from a W126
RE: Tires - EmJay - 08-27-2015
Never seen a non turbo diesel 300 here before. Guess we like our turbos here in the south, lol
RE: Tires - Petar - 08-27-2015
And i have never seen a turbo w123 myself here in Europe either
When you say 300D we automatically assume non turbo.
RE: Tires - Greazzer - 08-27-2015
yes, if your car is a 1985, it's most likely has the 2:88 which is desirable IMO. I think 85 is the only year for the 2:88, except some late production models in 1984. You can check the flange for the stamping. It will hide on you when you look, but once you see the flange, and clean off any crude, it's right there. 3 miles off is not too horrible. mine is off by a bunch ..lol