Did I purchase the wrong size tires???
03-15-12, 05:36 PM
#16
Instructor
Thread Starter
Okay let's break this down:
Stock Front: 225/40R18
Diameter: 25.1 in.
Stock Rear: 255/40R18
Diameter: 26.0 in.
New Front: 235/30R20
Diameter: 25.6 in.
New Rear: 275/30R20
Diameter: 26.5 in.
Difference between Stock Front and New Front: New is 1.9% larger
Difference between Stock Rear and New Rear: New is 1.8% larger
Difference between Stock Front and Stock Rear: Rear is 3.8% larger
Difference between New Front and New Rear: Rear is 3.7% larger
So no, these are not a problem, in fact they are closer in diameter between the front and the rear than the stock tires were on the RWD model. They will not damage or ruin anything unless you get rubbing from them being taller than stock, but that's just because of their height.
Most cars run the same diameter front and rear, including the AWD models, so for most cases he would be correct, but for a RWD the shop is definitely incorrect.
As for damaging the vehicle, that seems almost impossible, the vehicle speed signal to the ECU/Transmission comes from the rear wheels only, so it honestly doesn't care what the front wheels are doing, it will shift at the same "speed" as it always has. What can happen if you have sizes that are too different is the ABS/VSC may not react properly to differing wheel speeds in situations with skid, etc., though I've found that the 2IS ECU is quite adaptable and in most cases it probably would work just fine as well. The RWD IS250 has a wide variety of stock tire sizes and the ABS/VSC computers are always the same between them. This ranges from having the same sized tires all around (205/55R16) to the staggered diameters listed above. I run 205/50R17's all around on my RWD for the winter, and my VSC still works just dandy.
So are they the wrong size? They're a bit tall, but the difference between front and rear sizes? It is correct. Will anything get damaged? Not because of the size difference between them. Was the shop right? No they were not.
Jeff
Stock Front: 225/40R18
Diameter: 25.1 in.
Stock Rear: 255/40R18
Diameter: 26.0 in.
New Front: 235/30R20
Diameter: 25.6 in.
New Rear: 275/30R20
Diameter: 26.5 in.
Difference between Stock Front and New Front: New is 1.9% larger
Difference between Stock Rear and New Rear: New is 1.8% larger
Difference between Stock Front and Stock Rear: Rear is 3.8% larger
Difference between New Front and New Rear: Rear is 3.7% larger
So no, these are not a problem, in fact they are closer in diameter between the front and the rear than the stock tires were on the RWD model. They will not damage or ruin anything unless you get rubbing from them being taller than stock, but that's just because of their height.
Most cars run the same diameter front and rear, including the AWD models, so for most cases he would be correct, but for a RWD the shop is definitely incorrect.
As for damaging the vehicle, that seems almost impossible, the vehicle speed signal to the ECU/Transmission comes from the rear wheels only, so it honestly doesn't care what the front wheels are doing, it will shift at the same "speed" as it always has. What can happen if you have sizes that are too different is the ABS/VSC may not react properly to differing wheel speeds in situations with skid, etc., though I've found that the 2IS ECU is quite adaptable and in most cases it probably would work just fine as well. The RWD IS250 has a wide variety of stock tire sizes and the ABS/VSC computers are always the same between them. This ranges from having the same sized tires all around (205/55R16) to the staggered diameters listed above. I run 205/50R17's all around on my RWD for the winter, and my VSC still works just dandy.
So are they the wrong size? They're a bit tall, but the difference between front and rear sizes? It is correct. Will anything get damaged? Not because of the size difference between them. Was the shop right? No they were not.
Jeff
03-15-12, 07:04 PM
#17
check your connections and wiring. splicing a wire or two to get your new tail lights (whether OEM or aftermarket) to work can cause issues.
if all else fails, uninstall your new tail lights, un-do any splicing/re-wiring, and re-install your old tail lights.
/OT
Thread
Thread Starter
Forum
Replies
Last Post
neillexx
Wheels, Tires & Brakes Forum
5
04-10-06 10:26 PM
