different tires sizes front and back
different tires sizes front and back
Would having 215's in the front and 225's in the back offer any advantages or disadvantages on my 240? In my MR2 I had 215's in the front and 235's in the back, but granted it was pretty much standard to have tires wider in the back. So is there anything wrong with doing this? What are your set-ups?
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Grant@tirerack
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Grant@tirerack
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Q45tech
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The question of different sizes should consider that larger tires [higher load index ratings] have less slip angles for the same loaded weigh than lesser index tires.
This factor not necessarily the tread width is why designer use this concept.......many times it is a blend of the two.Don't ASSUME that wider tires always have a higher load index!
Almost always a RWD [or a FWD] has more friction potential on the lighest portion of the car. Until you start accelerating, then the total friction is proportioned between acceleration and handling [accelerating out of a curve] in a RWD.
The fronts are nearly always overloaded [engine weight] and the rear are underloaded by static weigh alone. Because manufacturers are allowed to spec only a 12% reserve.
Each tire has a different slope on the graph of friction vs loaded weigh.............the graph is linear [[1 LB of wight = 1 lb of friction x for tread compoud]] up to 75-80% of the maximum weight and inflation pressure. THEN the graph noses over and 1 lb of extra weight may only create 0.9 then 0.8 then 0.7 lbs of extra friction.Ideally one would want tires that have a FULL 25% or more reserve for the total static and handling weight. Unfortunately ~~~1650 pounds is the limit for street tires in V/Y/Z rating.limits.Racing slicks can have friction potential greater than 1.0:1 and street tires are around 0.85>0.9:1 and all season tires can be 0.75:1 and snow tires can be 0.60:1.
The reason all cars don't handle at 1.0 G is that the tires are overloaded by the handling forces. Larger stronger tires on the heaviest end will improve this.
Backwards from what most believe [in an understeering car] the strongest tires should be on the heaviest end.
In a powerful RWD car you must provide ample friction for both acceleration and simultaneous handling [or you get fish tailing and oversteer in acceleration].
This factor not necessarily the tread width is why designer use this concept.......many times it is a blend of the two.Don't ASSUME that wider tires always have a higher load index!
Almost always a RWD [or a FWD] has more friction potential on the lighest portion of the car. Until you start accelerating, then the total friction is proportioned between acceleration and handling [accelerating out of a curve] in a RWD.
The fronts are nearly always overloaded [engine weight] and the rear are underloaded by static weigh alone. Because manufacturers are allowed to spec only a 12% reserve.
Each tire has a different slope on the graph of friction vs loaded weigh.............the graph is linear [[1 LB of wight = 1 lb of friction x for tread compoud]] up to 75-80% of the maximum weight and inflation pressure. THEN the graph noses over and 1 lb of extra weight may only create 0.9 then 0.8 then 0.7 lbs of extra friction.Ideally one would want tires that have a FULL 25% or more reserve for the total static and handling weight. Unfortunately ~~~1650 pounds is the limit for street tires in V/Y/Z rating.limits.Racing slicks can have friction potential greater than 1.0:1 and street tires are around 0.85>0.9:1 and all season tires can be 0.75:1 and snow tires can be 0.60:1.
The reason all cars don't handle at 1.0 G is that the tires are overloaded by the handling forces. Larger stronger tires on the heaviest end will improve this.
Backwards from what most believe [in an understeering car] the strongest tires should be on the heaviest end.
In a powerful RWD car you must provide ample friction for both acceleration and simultaneous handling [or you get fish tailing and oversteer in acceleration].