Site for tire sizes and spedometers - 2003-04 Mach 1 Registry Owners Club

codymach · 03-12-2004, 05:56 PM

Here is site for those considering different tire sizes and how they will effect your spedometer....thought it may help!

www.miata.net/garage/tirecalc.html

Mach 10 · 03-12-2004, 09:05 PM

Thanks for the post

That's some good stuff to know:THUMBSUP:

JesseBolt · 03-12-2004, 11:15 PM

Thanks !!!

:OFFTOPIC: I recently installed 235/70/15 tires and rims on my beater that was stock 195/75/14. The site will be very helpful for getting the correct plastic gear that goes in the transmission. That calculation says my speedometer reading is 9.6% too slow and references a 60mph reading as actually traveling 65.7mph.

JB
Greenville, NC

Ralph Greene · 03-03-2005, 10:03 AM

There is no "correct" plastic gear for 99 an up cars. Use Speedcal or correct thru ECU.

Ralph Greene · 03-03-2005, 10:08 AM

This site gives same numbers as my trusty calculator, but keep in mind you're probably about 2-3% fast from factory, so some of the slightly larger than stock tire/wheel combo's are probably bringing you back into dead accurate speedo range....which is one reason I chose my slightly larger than stock diameter tires. Cody went one size larger than I did, and I bet he's either dead on or only slightly reading slow, no big deal, but enough to be careful if he runs thru his buddies radar gun.

palsar · 04-05-2007, 11:18 PM

According to that site, my new 315/35-17's will not change my speedometer reading from my stock 245/45-17's.

It gives the stock Revs/mile as 785.0 for both. Tirerack.com, where I bought my tires, give the Revs/mile as 808.0 for the 315's and the 245/45-17 as 811.

Anybody have an idea which is correct?

Macho 1 · 04-06-2007, 04:59 AM

The difference between the two is like .004% or about 20 ft every mile. At 60mph that is only a 1/4 mph difference. Don't think you will be able to blame the speeding tickets on the tires.

340.29_m/s · 04-06-2007, 10:52 AM

How about if I have 265/35/18 up front and 285/35/18 in the rear. Which one is the one that'll effect the speedo. I get 1.5% to fast with the 265 and 0.7% too slow with the 285. Do I just subtract on from the other. If that's the case 0.8% isn't too far off from factory wheels.

03bumblestang · 06-29-2008, 01:23 AM

That is pretty cool. I am getting new tires for my car, and it was very helpful!

mgk2 · 08-18-2008, 09:34 AM

Can anyone that uses this post respond to my change? I went from 245/45/17 to 275/40/18. Does my speedometer read different more or less accurately now?
Thank you,
Mike

newstang · 05-06-2010, 01:11 PM

what is the stock rim offset on 2004 mach?

MachGirl04 · 05-06-2010, 02:42 PM

I have 18s. I will often use my GPS as a speedometer b/c I am too lazy to do the math.

Lonestar7 · 05-07-2010, 12:21 AM

Just get a programer and change the tire size. Just more money for the addiction of owning a Mach.

LS:ORANGE:

03-12-2004, 05:56 PM	#1
codymach Registered User Join Date: Jun 2003 Location: somewhere Posts: 2,840	Site for tire sizes and spedometers Here is site for those considering different tire sizes and how they will effect your spedometer....thought it may help! www.miata.net/garage/tirecalc.html __________________ SUPPORTING MEMBER MODIFICATIONS: Bassani Mid-Length Ceramic Headers Bassani X-Pipe with cats SS Bassani Cat Back SS Meziere Electric water pump PHP Intake Spacer KN Filter Hurst Retro Shifter, T-handle Bullitt Fuel Door Bullitt Anthracite 18x9 wheels Goodrich g-force T/A KDW 265/40/18's Hurst Equipped Emblem Mach 1 I.D. Plate Shock tower covers Raised the shaker 2003 Mach 1 Torch Red 1965 Rambler Marlin 287 (Slowest car in the West!) 1951 Mercury (still in the field) 1966 Ford Galaxy 500, 352 cu. in. 4v 1994 F-150 4x4 2001 Focus

03-12-2004, 09:05 PM	#2
Mach 10 Slowmatic Join Date: Nov 2003 Location: Rockwall, Texas Posts: 635	Thanks for the post That's some good stuff to know:THUMBSUP: __________________ 04 Black Mach 1 (Auto) 12.882@105.14 Mach Garage 90 Red SC GT 12.456@111.39 GT Garage 96 Mystic Cobra 15.085@93.80 Cobra Garage 04 Bonneville SLE

03-03-2005, 10:03 AM	#4
Ralph Greene Registered User Join Date: Mar 2003 Location: Longwood Fl Posts: 3,724	Re: Site for tire sizes and spedometers There is no "correct" plastic gear for 99 an up cars. Use Speedcal or correct thru ECU. __________________ Ralph Greene SOLD 03 Mach 1 (Torch Red) 5 Speed Manual Real Ford FR 500 18X9 Wheels 255X40X18 Michelin Tires Steeda Sport Springs (isolators in) Tokico HP Struts/Shocks Steeda 4 bolt CC Plates Poly Offset Steering Rack Bushings Steeda TriAx Shifter Magnaflow X/Cats Bassani Catback with Removable Baffles

03-03-2005, 10:08 AM	#5
Ralph Greene Registered User Join Date: Mar 2003 Location: Longwood Fl Posts: 3,724	Re: Site for tire sizes and spedometers This site gives same numbers as my trusty calculator, but keep in mind you're probably about 2-3% fast from factory, so some of the slightly larger than stock tire/wheel combo's are probably bringing you back into dead accurate speedo range....which is one reason I chose my slightly larger than stock diameter tires. Cody went one size larger than I did, and I bet he's either dead on or only slightly reading slow, no big deal, but enough to be careful if he runs thru his buddies radar gun. __________________ Ralph Greene SOLD 03 Mach 1 (Torch Red) 5 Speed Manual Real Ford FR 500 18X9 Wheels 255X40X18 Michelin Tires Steeda Sport Springs (isolators in) Tokico HP Struts/Shocks Steeda 4 bolt CC Plates Poly Offset Steering Rack Bushings Steeda TriAx Shifter Magnaflow X/Cats Bassani Catback with Removable Baffles

04-05-2007, 11:18 PM	#6
palsar Registered User Join Date: Oct 2006 Location: Pittsfield, MA Posts: 161	Re: Site for tire sizes and spedometers According to that site, my new 315/35-17's will not change my speedometer reading from my stock 245/45-17's. It gives the stock Revs/mile as 785.0 for both. Tirerack.com, where I bought my tires, give the Revs/mile as 808.0 for the 315's and the 245/45-17 as 811. Anybody have an idea which is correct? __________________ 2003 TR IUP Auto - 60K Miles, 4:10s, MagnaFlow Cat-Bac, 31 spline Axles, SCT Tuner, JLT CAI, CircleD TQ, Mickey Thompson DR, 12.72 @ 105.67, 1.76 60'

04-06-2007, 04:59 AM	#7
Macho 1 Moose Magnet Join Date: Jan 2004 Location: Anchorage, Alaska Posts: 357	Re: Site for tire sizes and spedometers The difference between the two is like .004% or about 20 ft every mile. At 60mph that is only a 1/4 mph difference. Don't think you will be able to blame the speeding tickets on the tires. __________________ 04 Azure Blue Mach 1 K&N CAI, Steeda 2pt strut brace, Sport Springs, U&L Rear CA, & Tri-ax Shifter, SS Brakelines, X2 Balljoints and Adj Tie rods. Fiore Quadrant & MM CC Plates, HD Bilsteins, Roy's 1/2" spacer, XCal2, 17"x9" wheels, Bassani catted X, Magnaflow Catback RWHP: 285 @5100, FWTQ: 351@4300, FWHP 335@6100

04-06-2007, 10:52 AM	#8
340.29_m/s Registered User Join Date: Dec 2006 Location: Toronto Posts: 42	Re: Site for tire sizes and spedometers How about if I have 265/35/18 up front and 285/35/18 in the rear. Which one is the one that'll effect the speedo. I get 1.5% to fast with the 265 and 0.7% too slow with the 285. Do I just subtract on from the other. If that's the case 0.8% isn't too far off from factory wheels.

06-29-2008, 01:23 AM	#9
03bumblestang Registered User Join Date: Jun 2008 Location: Rohnert Park, CA Posts: 9	Re: Site for tire sizes and spedometers That is pretty cool. I am getting new tires for my car, and it was very helpful! __________________ What muffler?

08-18-2008, 09:34 AM	#10
mgk2 Registered User Join Date: Aug 2002 Location: Pembroke Pines,Fla Posts: 986	Re: Site for tire sizes and spedometers Can anyone that uses this post respond to my change? I went from 245/45/17 to 275/40/18. Does my speedometer read different more or less accurately now? Thank you, Mike

05-06-2010, 01:11 PM	#11
newstang Registered User Join Date: May 2010 Location: Portage, MI Posts: 1	Re: Site for tire sizes and spedometers what is the stock rim offset on 2004 mach?

05-06-2010, 02:42 PM	#12
MachGirl04 Registered User Join Date: Jun 2007 Location: IL Posts: 4,466	Re: Site for tire sizes and spedometers I have 18s. I will often use my GPS as a speedometer b/c I am too lazy to do the math. __________________ Angela -------------- 2004 Mach 1, Oxford White, Auto 18" Wheel Replica Magnum 500s, BFG KDWs, Borla Catback, K&N FIPKII, & too much bling to list 1994 T-Bird LX, V8, Black 1990 Mustang LX 5.0, Vert, 7-Up Special 2004 Mustang Coupe, V6, Torch Red ( That's all for now. )

05-07-2010, 12:21 AM	#13
Lonestar7 Guest Join Date: Apr 2007 Location: Denver, CO Posts: 3,152	Re: Site for tire sizes and spedometers Just get a programer and change the tire size. Just more money for the addiction of owning a Mach. LS:ORANGE:

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