New tires and tunning

csredfire07 · February 25th, 2007, 06:45 PM

Going from my CS 235\50\18's to a wider but thinner tire, say a 285\35\18, does the computer need to be re-tuned to compensate for the thinner dia. tire?

MustangMatt96GT · February 25th, 2007, 07:10 PM

If u want ur speedo to read correctly!

psycho bob · February 25th, 2007, 11:47 PM

i have the 285/40's in back and the tire hight is almost exactly the same as stock. i haven't done anything as far as a tuner goes and my speedo reads correctly. it's the same as the cop radar detector signs say as you pass them anyway

i think with the 285/35's you'll be off by a few miles per hour

csredfire07 · February 26th, 2007, 08:50 AM

I'm not too worried about the speed change as I am about the computer going into safe mode because of the rotation has changed between the tire and the rear. Same principal as changing the ring and pinion. Have to recalibrate the computer. Anyone know this answer? And thanks for your replies already.

ponyup · February 26th, 2007, 12:06 PM

I've been told by some pretty reputable car/tire guys that as long as you stay within 10% of the orginal tire diameter you should be ok.
Not sure where they're getting their information from but, they are the best source of information in my area.

MaverickMLFD371 · February 27th, 2007, 08:18 AM

Originally Posted by ponyup

I've been told by some pretty reputable car/tire guys that as long as you stay within 10% of the orginal tire diameter you should be ok.
Not sure where they're getting their information from but, they are the best source of information in my area.

yes he's correct. as long as the new tire size is within the range of the tuned tire size to the ECU, then you'll be fine, anything bigger, needs to be recalibrated

csredfire07 · February 27th, 2007, 08:26 AM

thanks guys for your imput. It just seems that whatever I do with this car, I have to have it retuned.

February 25th, 2007, 06:45 PM	#1
csredfire07 Newbie Join Date: Dec 2006 Location: northern NJ Posts: 43	New tires and tunning Going from my CS 235\50\18's to a wider but thinner tire, say a 285\35\18, does the computer need to be re-tuned to compensate for the thinner dia. tire?

February 25th, 2007, 11:47 PM	#3
psycho bob Hardcore Enthusiast 07 MUSTANG GT 12.86@104 Join Date: Aug 2006 Location: Ft. Hood, TX/ Tulsa, OK Posts: 2,130	i have the 285/40's in back and the tire hight is almost exactly the same as stock. i haven't done anything as far as a tuner goes and my speedo reads correctly. it's the same as the cop radar detector signs say as you pass them anyway i think with the 285/35's you'll be off by a few miles per hour __________________ JLT CAI, SCT Tuner, Eibach Pro Kit, D-specs, BMR LCA's, Adj. Panhard bar&support, Tri Axe w/ pistol grip, FRPP X-pipe, SLP loudmouths, Konig Beyond w/ BFG KDW's, MT ET Streets, black grill waiting install: GT/CS bumper, BMR shaft loops

February 26th, 2007, 12:06 PM	#5
ponyup Regular Join Date: Feb 2007 Location: Buffalo, NY Posts: 78	I've been told by some pretty reputable car/tire guys that as long as you stay within 10% of the orginal tire diameter you should be ok. Not sure where they're getting their information from but, they are the best source of information in my area. __________________ Seems ok, but could use more power

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February 25th, 2007, 07:10 PM	#2
MustangMatt96GT I Post Entirely Way Too Much 1996 Mustang GT 13.023@103.46 @ 5800 FT Join Date: Dec 2006 Location: Lakewood, CO Posts: 7,147	If u want ur speedo to read correctly!

February 26th, 2007, 08:50 AM	#4
csredfire07 Newbie Join Date: Dec 2006 Location: northern NJ Posts: 43	I'm not too worried about the speed change as I am about the computer going into safe mode because of the rotation has changed between the tire and the rear. Same principal as changing the ring and pinion. Have to recalibrate the computer. Anyone know this answer? And thanks for your replies already.

February 27th, 2007, 08:26 AM	#7
csredfire07 Newbie Join Date: Dec 2006 Location: northern NJ Posts: 43	thanks guys for your imput. It just seems that whatever I do with this car, I have to have it retuned.

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