Wider Tires on a AWD
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#8
Tire width shouldn't have any bearing on AWD performance. And as you know the oem sizes are staggered setup and are wider on rears than fronts.
What AWD is sensitive to is rolling diameter. If you have a meaningful difference btw the diameter of the front and the rear wheels then the wheels at front and rear have to rotate at different speeds and that can mess up some AWD systems
I had national chain tell me they wouldn't replace just the one punctured tyre in my Land Rover as the others were down to 7mm and the new tire would be 11mm tread. They claimed that difference would damage the car. So they tried (unsuccessfully) to sell me all four!
LR disagreed (as did I) and I never had any issues
What AWD is sensitive to is rolling diameter. If you have a meaningful difference btw the diameter of the front and the rear wheels then the wheels at front and rear have to rotate at different speeds and that can mess up some AWD systems
I had national chain tell me they wouldn't replace just the one punctured tyre in my Land Rover as the others were down to 7mm and the new tire would be 11mm tread. They claimed that difference would damage the car. So they tried (unsuccessfully) to sell me all four!
LR disagreed (as did I) and I never had any issues
#9
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powerhouse (06-06-2020)
#10
I use to have a B4 and B8 Audi S4's and with quattro staggered fit is a no no, the car must have square fitment (same wheel and tires size on all 4) there must be the same amount of rubber (width) on the ground from all 4 corners and to avoid the chance of damaging the differential.
I'm not sure about F Type AWD but since they come staggered from the factory, going from 295 to 305 shouldnt be an issue.
I'm not sure about F Type AWD but since they come staggered from the factory, going from 295 to 305 shouldnt be an issue.
Last edited by wurldfamuz; 06-05-2020 at 02:10 AM.
#11
I was going to fit the Mich 305's now and leave the fronts as there are newish 255 Pirellis on (3k miles) was going to put Mich 265's on when bit more run out of the Pirellis. So its a no can do and must bin Pirellis ! just as well the pubs are shut ! But excuse me if I am coming over thick I get the different diameters but how would changing the width effect the motor. simple terms please would be appreciated.
Last edited by shaun james; 06-05-2020 at 03:03 AM.
#12
I was going to fit the Mich 305's now and leave the fronts as there are newish 255 Pirellis on (3k miles) was going to put Mich 265's on when bit more run out of the Pirellis. So its a no can do and must bin Pirellis ! just as well the pubs are shut ! But excuse me if I am coming over thick I get the different diameters but how would changing the width effect the motor. simple terms please would be appreciated.
Coz the overall tyre diameter difference between front and rear might be outside of the parameters the computer(s) are set for.
305/30s on the rear will be a tad taller (greater diameter) than the stock 295/30s and should be OK and within tolerance with stock 255/35s on the front but don't quote me on that!
I seem to recall that the Unhingd one has posted about this somewhere.
Note that the F-Type SVR (AWD) comes stock with 305/30 rear and 265/35 front.
#13
What AWD is sensitive to is rolling diameter. If you have a meaningful difference btw the diameter of the front and the rear wheels then the wheels at front and rear have to rotate at different speeds and that can mess up some AWD systems
I had national chain tell me they wouldn't replace just the one punctured tyre in my Land Rover as the others were down to 7mm and the new tire would be 11mm tread. They claimed that difference would damage the car. So they tried (unsuccessfully) to sell me all four!
I had national chain tell me they wouldn't replace just the one punctured tyre in my Land Rover as the others were down to 7mm and the new tire would be 11mm tread. They claimed that difference would damage the car. So they tried (unsuccessfully) to sell me all four!
#14
To clear some things up here.... as said before, width doesn't matter. The rolling circumference is what's important when it comes to AWD systems. Some systems are more sensitive than others, but for systems like ours with a clutch style center differential, you don't want to be messing with different diameters front to rear. For example, if you run a tire with a 650 revolution per mile diameter in the front, and a tire with a 640 rev per mile diameter in the rear, the center differential has to physically slip to account for the 10 revolutions difference between the front and rear every mile. This can excessively wear the center differential extremely quickly and make the AWD system basically useless when it fails.
The difference between 650 rev/mile and 640 rev/mile is only 13mm across what is a 31" tall tire, or just 6.5mm of sidewall height. That's the difference between a brand new tire and a worn tire of the exact same size.
Some AWD/4WD systems have mechanically locking center differentials which can result in the tires slipping as opposed to damage to the driveline. But the F-type center differential is a part time clutch style system, which only engages when the wheels are slipping, or the vehicle is under heavy load. With this, everything is okay until it isn't. The system can handle some difference front to rear, but how much it can tolerate is anyone's guess. Best not to mess with it just for a bit more aggressive look.
Important to keep in mind; changing width of a tire also effects its overall diameter. Some people don't realize that the sidewall height portion of the tire spec is a percentage of the width, not an actual measurement.
295/30 = 88.5 mm sidewall
305/30 = 91.5 mm sidewall
The difference between 650 rev/mile and 640 rev/mile is only 13mm across what is a 31" tall tire, or just 6.5mm of sidewall height. That's the difference between a brand new tire and a worn tire of the exact same size.
Some AWD/4WD systems have mechanically locking center differentials which can result in the tires slipping as opposed to damage to the driveline. But the F-type center differential is a part time clutch style system, which only engages when the wheels are slipping, or the vehicle is under heavy load. With this, everything is okay until it isn't. The system can handle some difference front to rear, but how much it can tolerate is anyone's guess. Best not to mess with it just for a bit more aggressive look.
Important to keep in mind; changing width of a tire also effects its overall diameter. Some people don't realize that the sidewall height portion of the tire spec is a percentage of the width, not an actual measurement.
295/30 = 88.5 mm sidewall
305/30 = 91.5 mm sidewall
Last edited by Stohlen; 06-06-2020 at 09:44 PM.
#15
To clear some things up here.... as said before, width doesn't matter. The rolling circumference is what's important when it comes to AWD systems. Some systems are more sensitive than others, but for systems like ours with a clutch style center differential, you don't want to be messing with different diameters front to rear. For example, if you run a tire with a 650 revolution per mile diameter in the front, and a tire with a 640 rev per mile diameter in the rear, the center differential has to physically slip to account for the 10 revolutions difference between the front and rear every mile. This can excessively wear the center differential extremely quickly and make the AWD system basically useless when it fails.
The difference between 650 rev/mile and 640 rev/mile is only 13mm across what is a 31" tall tire, or just 6.5mm of sidewall height. That's the difference between a brand new tire and a worn tire of the exact same size.
Some AWD/4WD systems have mechanically locking center differentials which can result in the tires slipping as opposed to damage to the driveline. But the F-type center differential is a part time clutch style system, which only engages when the wheels are slipping, or the vehicle is under heavy load. With this, everything is okay until it isn't. The system can handle some difference front to rear, but how much it can tolerate is anyone's guess. Best not to mess with it just for a bit more aggressive look.
Important to keep in mind; changing width of a tire also effects its overall diameter. Some people don't realize that the sidewall height portion of the tire spec is a percentage of the width, not an actual measurement.
295/30 = 88.5 mm sidewall
305/30 = 91.5 mm sidewall
The difference between 650 rev/mile and 640 rev/mile is only 13mm across what is a 31" tall tire, or just 6.5mm of sidewall height. That's the difference between a brand new tire and a worn tire of the exact same size.
Some AWD/4WD systems have mechanically locking center differentials which can result in the tires slipping as opposed to damage to the driveline. But the F-type center differential is a part time clutch style system, which only engages when the wheels are slipping, or the vehicle is under heavy load. With this, everything is okay until it isn't. The system can handle some difference front to rear, but how much it can tolerate is anyone's guess. Best not to mess with it just for a bit more aggressive look.
Important to keep in mind; changing width of a tire also effects its overall diameter. Some people don't realize that the sidewall height portion of the tire spec is a percentage of the width, not an actual measurement.
295/30 = 88.5 mm sidewall
305/30 = 91.5 mm sidewall
255/35 = 89.25 mm sidewall
265/35 = 92.75 mm sidewall
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