What is your tire pressure?
#16
Lexus Test Driver
Last edited by bclexus; 03-10-16 at 04:52 PM.
#17
#18
Lexus Test Driver
#19
#20
I have an awd f sport and the tire size is 235/40r19 ( all 4 tires ). The regular gs model has 18" tires which are not low profile. Larger tires require more psi plus f sport vehicles weigh more
#21
Lexus Test Driver
Lexus recommends the non-F-Sport tires (235/45R18-94) be inflated to 33 psi cold, which provides a load limit of 1,378 lbs per tire. (See attachment)
Lexus recommends the F-Sport tires (Front 235/40R19-92 & Rear 265/35R19-94) be inflated to 35 psi and 36 psi cold respectively, which provides a load limit of 1,345 lbs per tire and 1,477 lbs per tire respectively. (See attachment)
Note: As noted in the attachments below these tires do not benefit in higher load limit ratings from being inflated to greater than 36 psi.
I'm a bit confused...because I would have thought that Lexus would want the tire psi to provide the same approximate load ratings at each corner. It is the same with the non-F-Sport because all four tires are the same size and inflated to the same psi. However with the F-Sport, the front tires are inflated to have almost the identical load rating as the non-F-Sport (1,345 vs 1,378), but the rear tires of the F-Sport are inflated to have a substantially higher load rating (1,477 vs 1,378). If the rear tires of the F-Sport were inflated to 33 psi (instead of 36 psi as recommended) the load rating of the rear tires would become 1,378 lbs, which nearly matches the load rating of front tires and exactly matches the load rating of the non-F-Sport tires. In looking for the reason that Lexus wants the rear tires of the F-Sport to carry more load - it is not the weight distribution, because the car is weighted at 53% front versus 47% rear. Maybe Lexus wants the F-Sport to produce oversteer characteristics. I dunno...
Lexus recommends the F-Sport tires (Front 235/40R19-92 & Rear 265/35R19-94) be inflated to 35 psi and 36 psi cold respectively, which provides a load limit of 1,345 lbs per tire and 1,477 lbs per tire respectively. (See attachment)
Note: As noted in the attachments below these tires do not benefit in higher load limit ratings from being inflated to greater than 36 psi.
I'm a bit confused...because I would have thought that Lexus would want the tire psi to provide the same approximate load ratings at each corner. It is the same with the non-F-Sport because all four tires are the same size and inflated to the same psi. However with the F-Sport, the front tires are inflated to have almost the identical load rating as the non-F-Sport (1,345 vs 1,378), but the rear tires of the F-Sport are inflated to have a substantially higher load rating (1,477 vs 1,378). If the rear tires of the F-Sport were inflated to 33 psi (instead of 36 psi as recommended) the load rating of the rear tires would become 1,378 lbs, which nearly matches the load rating of front tires and exactly matches the load rating of the non-F-Sport tires. In looking for the reason that Lexus wants the rear tires of the F-Sport to carry more load - it is not the weight distribution, because the car is weighted at 53% front versus 47% rear. Maybe Lexus wants the F-Sport to produce oversteer characteristics. I dunno...
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signdetres (12-14-18)
#22
I was surprised when I first noticed 35-36ish on my sister's F Sport (before I got mine). I thought it was the high psi that made hers more road noticeable compared to my 18. I almost told her to run at 32-33. I checked and saw it's recommended at higher psi than non F sport. I'm not a tire guy but I think it's due to the low profile. Lower psi on 19 would increase the chance a tire would pop when one goes over a pot hole.
#23
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Thanks to everyone who gave me their input on this matter! very helpful... it makes me feel more comfortable that I ride between 35 to 37... BUT this morning when I got in my car the pressure read 31... now granted it was cold so I get its usually low in the mornings but I just feel its way too low and will I think wear my tires out quicker. When they warmed up it went to 35.
I think I am going to bring my pressure up to 38... if I have them at 40, when its cold I figure it would drop to 35 and then its hot maybe about 40 I don't want to damage my rims or wear out my tires too quick.
Does anyone know the range the pressure hangs in? 5 up 5 down?
I think I am going to bring my pressure up to 38... if I have them at 40, when its cold I figure it would drop to 35 and then its hot maybe about 40 I don't want to damage my rims or wear out my tires too quick.
Does anyone know the range the pressure hangs in? 5 up 5 down?
#24
Lexus Test Driver
For every 10° change in temperature the tire pressure will change ±1 psi. Daily climate normally changes temperature ~20° from low to high - so about 2 psi can be contributed temperature change.
During sunny, clear days the sun's radiation alone will cause the tire pressure to increase by ~1 to 2 psi.
Driving will naturally increase the tire pressure by ~2 to 3 psi, but if the road surface is black asphalt during very hot sunny, summer weather the tire pressure could increase by an additional ~1 or 2 psi.
So, all-in-all, from a 'cold' tire pressure where the vehicle has been parked overnight in a dark garage there would most likely be an increase of ~5 psi for a typical day in most regions of the country. But if the day is heavily overcast with thick clouds and the temperature doesn't increase much throughout the day then the tire pressure may only increase by ~2 to 3 psi. In places where the ambient temperature often gets to 100° or higher the tire pressure increase could increase by 8 psi.
Your best bet would be to set your tire pressure (according to the door jamb label) early in the early morning after the vehicle has been parked overnight (e.g. 'cold') in a dark garage (with no sun radiation).
During sunny, clear days the sun's radiation alone will cause the tire pressure to increase by ~1 to 2 psi.
Driving will naturally increase the tire pressure by ~2 to 3 psi, but if the road surface is black asphalt during very hot sunny, summer weather the tire pressure could increase by an additional ~1 or 2 psi.
So, all-in-all, from a 'cold' tire pressure where the vehicle has been parked overnight in a dark garage there would most likely be an increase of ~5 psi for a typical day in most regions of the country. But if the day is heavily overcast with thick clouds and the temperature doesn't increase much throughout the day then the tire pressure may only increase by ~2 to 3 psi. In places where the ambient temperature often gets to 100° or higher the tire pressure increase could increase by 8 psi.
Your best bet would be to set your tire pressure (according to the door jamb label) early in the early morning after the vehicle has been parked overnight (e.g. 'cold') in a dark garage (with no sun radiation).
#25
thanks man for those tips, its too bad i have a cheap air compressor, it will take like 10 mins to get it up few psi.
For every 10° change in temperature the tire pressure will change ±1 psi. Daily climate normally changes temperature ~20° from low to high - so about 2 psi can be contributed temperature change.
During sunny, clear days the sun's radiation alone will cause the tire pressure to increase by ~1 to 2 psi.
Driving will naturally increase the tire pressure by ~2 to 3 psi, but if the road surface is black asphalt during very hot sunny, summer weather the tire pressure could increase by an additional ~1 or 2 psi.
So, all-in-all, from a 'cold' tire pressure where the vehicle has been parked overnight in a dark garage there would most likely be an increase of ~5 psi for a typical day in most regions of the country. But if the day is heavily overcast with thick clouds and the temperature doesn't increase much throughout the day then the tire pressure may only increase by ~2 to 3 psi. In places where the ambient temperature often gets to 100° or higher the tire pressure increase could increase by 8 psi.
Your best bet would be to set your tire pressure (according to the door jamb label) early in the early morning after the vehicle has been parked overnight (e.g. 'cold') in a dark garage (with no sun radiation).
During sunny, clear days the sun's radiation alone will cause the tire pressure to increase by ~1 to 2 psi.
Driving will naturally increase the tire pressure by ~2 to 3 psi, but if the road surface is black asphalt during very hot sunny, summer weather the tire pressure could increase by an additional ~1 or 2 psi.
So, all-in-all, from a 'cold' tire pressure where the vehicle has been parked overnight in a dark garage there would most likely be an increase of ~5 psi for a typical day in most regions of the country. But if the day is heavily overcast with thick clouds and the temperature doesn't increase much throughout the day then the tire pressure may only increase by ~2 to 3 psi. In places where the ambient temperature often gets to 100° or higher the tire pressure increase could increase by 8 psi.
Your best bet would be to set your tire pressure (according to the door jamb label) early in the early morning after the vehicle has been parked overnight (e.g. 'cold') in a dark garage (with no sun radiation).
#26
Lexus Test Driver
I use a digital air pressure gauge that I know is accurate because it compares exactly with a known lab calibrated gauge.
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