16 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHInaccurate speedo
Leading reported evidence
Check gps speed and guess what it was
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
As I was at 60 MPH I decided to check the GPS speed and guess what it was.....
Leading evidence: 'Check gps speed and guess what it was' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check gps speed and guess what it was' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
16 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T220748Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
No, not the bathing suit.
It seems that my speedometer is overstating my speed by several mph even just in the 40 mph range. Tires 225/40 ZR18 and 265/35 ZR18 tires. Are those standard tire sizes? Any other ideas what could be causing it? I need to get the wife to pace me in her car so I can see how far off I am.
Thanks in advance.
My car was lowered aggressively by the PO. front fender is 24 5/8 from the ground over the wheel center line. rear fender is 24 3/8.
I was wondering if maybe the PO put smaller circumference tires so thay would not rub. The rear tires go up behind the fender by half an inch or so.
Normal
225/265 is stock for 18�s
They do it for a reason. If it was the the other way around and your actual speed was faster than what it showed and you got a ticket or an major accident you would have a claim against Porsche.
The Miles you are traveling should be accurate. My speed shows higher than it is but the Miles driven are right on.
Honda just settled a class action law suit regarding customer odometers.
The odometers would rack up miles faster than what a real mile was, and by that happening Honda had vehicles go out of warranty faster and it would save them MILLIONS in warranty claims.
This happens on all German cars, by law in Germany, a
car's speedometer must never read slower than actual speed.
Therefore, to account for variables in production and
things like tire wear, German speedometers are
calibrated to give a "cushion" on the high side.
One thing that has always driven me a little crazy is that the analog speedometer is ever so slightly different than the digital speedometer. For example, when I'm going 60mph on the digital, the analog reads 59mph. Of course, it only drives me crazy when I look at the analog, which is never, but still. Any idea which one is more accurate?
Bringing up an old thread here but...
So it is safe to say that the miles travelled IS accurate?
I notice it now because I have a lot of those posted radar speed signs near my kids school. In my old car, the speedo would say 40mph and the sign would say 40mph. In the P-car, sign says about 37mph and the speedo says 40.
I've found the digital speed consistently over-reads by 4mph in the range 12-163mph. I also found that over a 90 mile course measured by GPS and civil engineers, the mileage over-reads by 2.3 miles at road speeds, and 2.4-2.5 miles at speeds over 120 mph...
All on stock 2002 18s, 225/285.
I think you could minimize the error somewhat by selecting a slightly larger tire diameter. Even the same sized tires will have different diameters from different tire manufacturers. Michelin might by .1-.2 inches smaller than Goodyear, for instance. Tirerack.com shows all the actual widths, diameters, and weights of all the tires, so maybe if you are going to choose between two tire brands, pick the one that has more diameter. Remember of course more diameter means slightly less acceleration, and higher top speed.
Funny that I stumbled upon this thread, last night I was hauling a car with my 2002 Dodge 24-Valve Cummins Turbo Diesel Ext Cab Dully (6-spd manual) and had a GPS hooked up. As I was at 60 MPH I decided to check the GPS speed and guess what it was..... yep, exactly 60MPH. I couldn't believe how dead-on the speedo was. Immediately I thought of how the hell can my 911 speedo be off by 4-5 MPH if a Dodge can make one dead-on!!!
This is a source reference. Confirm exact model applicability in the original material.
