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Question about tires...
Thread Starter
Instructor
Joined: Mar 2008
Posts: 138
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From: Monroe NY
Question about tires...
Hey everyone, well over the summer I bought 2 new tires for my stock rear rims (18 inch), and never got around to putting them on. Now instead of putting them on my stock wheels im actually looking to get new ones all together-18s front 19s rear. Can I use these tires on the front?-(im not sure about the width of that size wheel in the front) and also, what is the rule with this set up... Do the front and rear tires have to be the same kind? (same tread pattern that is)?-I only drive on the street so there is no track racing if that helps in an explanation. thanks in advance and sorry if these questions sound ridiculous
Race Director
Joined: Nov 2004
Posts: 11,070
Likes: 1,293
From: Central Ma
The tires you bought could be used on the front with 18x9.5 wheel.
Most people would then do 19x10.5 or 11.
You want a difference of at least 1/2" in height front to rear. Use the below calculator to see for yourself.
I know each axle should have the same tires, but I don't think it's a must to match the front and rear. I would want the same all around.
You should not mix rf's and non rf's.
I'm not a tire expert, so confirm this info first.
Hope this helps.
http://www.miata.net/garage/tirecalc.html
Most people would then do 19x10.5 or 11.
You want a difference of at least 1/2" in height front to rear. Use the below calculator to see for yourself.
I know each axle should have the same tires, but I don't think it's a must to match the front and rear. I would want the same all around.
You should not mix rf's and non rf's.
I'm not a tire expert, so confirm this info first.
Hope this helps.
http://www.miata.net/garage/tirecalc.html
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
Want to reduce acceleration, ride quality, and braking ability? It's simple, buy some larger, heavier wheels!
Seriously, You WILL hurt performance unless you pay attention to wheel/tire weight. Try to stay at or under the weight of each combo as it came from the factory.
Seriously, You WILL hurt performance unless you pay attention to wheel/tire weight. Try to stay at or under the weight of each combo as it came from the factory.
Race Director
Joined: Aug 2003
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From: "It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark, and
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-‘18-'19
NCM Sinkhole Donor
Generally - a 275-40x18 is too tall of a tire for the front. I assume that's what you bought.
As an example - I run a 275-35x18 in front and a 305-30x19 in back, the rule of thumb is to make sure that the back set is slightly taller than the fronts, so that the revolutions per mile in back is less than the front, meaning the backs are spinning slower than the fronts. As long as you maintain this "stagger", you won't have any issues with the traction control system.
As an example - I run a 275-35x18 in front and a 305-30x19 in back, the rule of thumb is to make sure that the back set is slightly taller than the fronts, so that the revolutions per mile in back is less than the front, meaning the backs are spinning slower than the fronts. As long as you maintain this "stagger", you won't have any issues with the traction control system.
Le Mans Master
Joined: Apr 2003
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From: Palm Bay FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11
Instructor
Joined: Nov 2007
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From: Peoria Arizona
Im not trying to hi jack anyones thread but I have a related question. A car I am currently looking at the owner put new rims ( Weld XL ) and tires ( Michelin non RF ) on. He put 18's front and rear because he didn't like the rear higher. Any harm in this with the traction control operation as you describe. If so how?
Race Director
Joined: Aug 2003
Posts: 16,270
Likes: 30
From: "It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark, and
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-‘18-'19
NCM Sinkhole Donor
Im not trying to hi jack anyones thread but I have a related question. A car I am currently looking at the owner put new rims ( Weld XL ) and tires ( Michelin non RF ) on. He put 18's front and rear because he didn't like the rear higher. Any harm in this with the traction control operation as you describe. If so how?
What size tires are being run - front and back?
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Thread Starter
Instructor
Joined: Mar 2008
Posts: 138
Likes: 0
From: Monroe NY
Generally - a 275-40x18 is too tall of a tire for the front. I assume that's what you bought.
As an example - I run a 275-35x18 in front and a 305-30x19 in back, the rule of thumb is to make sure that the back set is slightly taller than the fronts, so that the revolutions per mile in back is less than the front, meaning the backs are spinning slower than the fronts. As long as you maintain this "stagger", you won't have any issues with the traction control system.
As an example - I run a 275-35x18 in front and a 305-30x19 in back, the rule of thumb is to make sure that the back set is slightly taller than the fronts, so that the revolutions per mile in back is less than the front, meaning the backs are spinning slower than the fronts. As long as you maintain this "stagger", you won't have any issues with the traction control system.
Is a tire of that size (275-40x18) going to rub? Am I not going to be able to use these tires in the front than? -and thanks everyone,I always love some good advice and took everyones suggestions into consideration.
Race Director
Joined: Aug 2003
Posts: 16,270
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From: "It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark, and
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-‘18-'19
NCM Sinkhole Donor
I guess the only way to tell is mount it on the front and see....
Drifting
Joined: Jul 2007
Posts: 1,365
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As stated by BlackSedan87 having the same diameter rims front and rear is not a problem. What becomes a problem is not maintaining the rear tires having an outside diameter of at least 1/2 inch taller than the outside diameter of the front tires. GM designed the Traction Control (TC) system such that it expects the rear tires to be turning slower than the front tires. This is accomplished by the larger outside diameter on the rear. The 1/2 inch larger is generally considered safe since rear tires for some yet to be determined reason 
wear more quickly than the fronts. If the TC system determines that the rear tires are turning as fast or more fast than the fronts it begins pulsing the rear brakes, reducing both fuel and timing advance as it tries to correct the "problem". You can turn off the TC system to prevent this (Drag racers do it all the time) but this is generally not adviced as an "all the time" solution.
wear more quickly than the fronts. If the TC system determines that the rear tires are turning as fast or more fast than the fronts it begins pulsing the rear brakes, reducing both fuel and timing advance as it tries to correct the "problem". You can turn off the TC system to prevent this (Drag racers do it all the time) but this is generally not adviced as an "all the time" solution.Im not trying to hi jack anyones thread but I have a related question. A car I am currently looking at the owner put new rims ( Weld XL ) and tires ( Michelin non RF ) on. He put 18's front and rear because he didn't like the rear higher. Any harm in this with the traction control operation as you describe. If so how?