changed tires information - Help
Thread Starter
Instructor
Joined: Feb 2005
Posts: 144
Likes: 0
From: Oklahoma City Oklahoma
changed tires information - Help
I changed tires from 255 - 40 - 17 front, 285 - 35 - 18 rear to 275 - 40 - 18 front and 305 - 35 - 18. Traction Control acting very erratic...my rims are 9.5 and 10.5...Looks great - Nittos...Need your help...
Race Director
Joined: Jul 2004
Posts: 16,795
Likes: 62
From: Lake Havasu City, AZ
side wall height in inches on your old tires is 4.0 front, 3.9 rear
(255x.40)/25.4 front (285x.35)/25.4 rear
The new tires side walls are 4.3 front and 4.2 rear.
In both cases the front tire sidewall is 0.1 inches higher than the rear. So that should not be causing you a problem.
(255x.40)/25.4 front (285x.35)/25.4 rear
The new tires side walls are 4.3 front and 4.2 rear.
In both cases the front tire sidewall is 0.1 inches higher than the rear. So that should not be causing you a problem.
Safety Car
Joined: Nov 2004
Posts: 4,843
Likes: 2
From: West Michigan
St. Jude Donor '06-'07-'08-'11, '14
Your stock tires are:
245-45 17 = 25.68 diameter front
275-40 18 = 26.6 diameter rear
Approx. 1" BIGGER in the rear.
Your current size:
275-40 18 = 26.6 diameter front
305-35 18 = 26.4 diameter rear
Approx .2" SMALLER in the rear.
Your traction control thinks the rear tires are spinning too fast.
245-45 17 = 25.68 diameter front
275-40 18 = 26.6 diameter rear
Approx. 1" BIGGER in the rear.
Your current size:
275-40 18 = 26.6 diameter front
305-35 18 = 26.4 diameter rear
Approx .2" SMALLER in the rear.
Your traction control thinks the rear tires are spinning too fast.
Race Director
Joined: Jul 2004
Posts: 16,795
Likes: 62
From: Lake Havasu City, AZ
I re did my math... and stand corrected... instead of the short cut of just looking at sidewall height differences , I calclulated wheel height and I agree with TLS.
The only difference is he calclulated stock to new....
I calculated old to new...
Old front tire height 25.03 inches Rear tire height 25.85
The old rears where larger by 0.8 inches
New tire height front 26.7 rear 26.4
new rear tires smaller by 0.3 inches
That is your problem......
The only difference is he calclulated stock to new....
I calculated old to new...
Old front tire height 25.03 inches Rear tire height 25.85
The old rears where larger by 0.8 inches
New tire height front 26.7 rear 26.4
new rear tires smaller by 0.3 inches
That is your problem......
Team Owner
Joined: Mar 2002
Posts: 47,647
Likes: 1
From: Queens, New York Life begins at 183 mph....
St. Jude Donor '08-'09
I have a set of Nitto 555 RIIs, they are 285 35 18s in the front, 305 35 18s in the rear. No traction problems at all. I don't know if you can fit a 285 35 18 tire on a 9.5 inch rim though, my fronts are 10. It might work. If not, see if Nitto makes a 275 35 18 tire. Make sure that you don't mix tire brands or else you'll get other handling problems.
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