Like it was stated earlier, the wheel diameter doesn't really matter. What matters is the circumference of the tire. If you increase the wheel diameter and decrease the aspect ratio, you should still have a similar wheel circumference.
For example, when putting 235's on a 17 inch wheel, the stock aspect ratio is 55% for a 2007 GT coupe, resulting in a sidewall of 129.25mm. This puts the overall diameter at about 27.1in with 767 revs/mile. (You'll notice that tirerack.com usually tells you how many rotations per mile a tire makes).
With a 20 inch wheel, a 255/35 sized tire is needed to maintain the stock circumference. This setup yields a 89.25 mm sidewall with an overall diameter of 27.0 inches and 763 revs/mile, which is close enough to stock, so the speed should be off by .4mph @70mph at the most. If the tires are 275/35,however, then the overall diameter will be 27.6 inches with 747revs/mile, which is half an inch off stock, and speed should be off by a little over 1mph @ 70mph.
If the tires that you have on the car have an overall diameter that is much higher than stock, then the circumference will noticeably increase, and the actual speed of the vehicle will be higher than indicated since the wheels are making the same number of rotations, but covering more distance with each rotation (lower revs/mile). Imagine rolling a small wheel 100 times, and a huge wheel 100 times. The large wheel will go much, much further. Sorry for the long explanation, but I did not know what size tires you have. Like was stated previously, you would need a rediculously huge overall diameter to have an error of 15mph@70mph indicated.
I can't give you any legal advice, since I have no experience with courts whatsoever, but if you want to use the math in court, there are many calculators on the internet to find indicated vs actual speed with varying tire sizes, and tirerack has many measurements to use, though I don't know if that will help your case.
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2001 SVT Cobra
Bassani x-pipe, Flowmasters, MM Subframe connectors, MM delrin (rear) and polyurethane (front) bushings, MM four point strut tower brace
Okay so i do have a clean record. I guess i will have it re-calibrated and go to court. Who would i need to get it calibrated? is is something only ford can do? and how much do you think that would cost? Thanks
I deal with this all day long, every day, as I work in a very busy court. First off, like everyone else has mentioned: check with the court on deferrals. Some don't even offer them, but in order to prevent the ticket from even reaching DOL, you have to keep it "in house", aka at the courthouse. In our court, that means having a clean record and paying the face value of the ticket in full THAT DAY. If you go violation-free for another year, it's dismissed and never sees DOL's eager little hands. If it's a $500 ticket, I'd think twice about taking the deferral, as I doubt your insurance will go up that much. If it's $124...well, I'd take it. Of course, this entails you pleading guilty to the charge. And once you plead guilty, it's very difficult to get a judge to accept a change to a not guilty plea. And you only get one deferral once every 7 years. So use it wisely.
The flipside of the coin means fighting it tooth and nail. Your problem is, you already admitted to the officer that your odo wasn't correctly calibrated. 'Nuf said; you were speeding. IF, and only IF, he didn't put that admission into his affidavit, then I say you might have a chance of pleading innocence of the odo prob. You can request a copy of his affidavit, and a copy of the radar's certification. You can also subpoena the officer & have him testify at a trial.
Of course, all of the above is for my particular court in my particular state, and all courts operate differently.
As far as judges just ripping through these calendars just to rake in the money...I have to say that about 90% of the money received in tickets goes right back to the state - not the municipality or the county that wrote you the ticket.
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FORD: Drive One (or two...or three...or four...or...)
'66 dark blue (Night Mist-ish) coupe Restomod (Sparky)
'07 Metallic Alloy V-6 w/ GT cosmetic upgrades (Annie)
'71 Grabber Lime fastback - 1 of 617 (Miss Demeanor)
'97 F-250 diesel (Big Ed...don't ask)
As far as judges just ripping through these calendars just to rake in the money...I have to say that about 90% of the money received in tickets goes right back to the state - not the municipality or the county that wrote you the ticket.
This is so true, I deal with people saying you people just want money all day long. Sad but true, most of the money goes to other agencies throughout the county and state, very little stays within the municipalities.
DUI fines are the worst. Those can be as high as 5000.00 (and higher) only 250.00 stays in the city the rest goes everywhere else. We become a collection agency for the state and county.
Again, check your laws, call the court and ask for your options! They should tell you what you can expect and what you can and cannot do!
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Getting ready to love life again! Dreams do come true! __________________________________________________ 2006 Mustang GT
I for one am so glad this has NOT turned into yet another "I hate the cops" thing.
Oh yes, there's methods they have to check your speed and no radar will EVER pick up. Depending on a detector only tells you when you're being clocked, not before because it's getting the beams. By the time it goes off, you're on the clock and he has you.
Since this is your first offense, most of the time the DA will reduce the charge to a more manageable speed and you just pay a fine.
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