Tire Rack - Question Please
12-29-2014, 12:01 AM
#1
Rennlist Member
Thread Starter
Tire Rack - Question Please
Tire Rack, question on load ratings. A forum member, 997, from Dubai, complained about a squirmy driving car. A lot of speculation and good ideas from fellow members. I recall having a similar issue with my wifes Porsche, where the shop accidentally ordered/installed non-XL rated tires and the car was extremely squirmy until we discovered that and they corrected it.
When I asked this forumer to check his tires, he did and while the tires are the same brand, pattern etc, they have XL load in rear and non-XL load in front. I told him I was pretty sure that was his issue due to fronts reacting differently than rears due to different stability from the load ratings. He had checked a couple of websites, Michelin UK and one said Porsche 997 should have both front and rear XL while another said front standard load and rear XL. Which makes no sense. Can you help clear up so I can send him your professional advice? What is your take on his car having SL fronts and XL rears...potentially the issue or not a problem, check elsewhere?
Thank you
When I asked this forumer to check his tires, he did and while the tires are the same brand, pattern etc, they have XL load in rear and non-XL load in front. I told him I was pretty sure that was his issue due to fronts reacting differently than rears due to different stability from the load ratings. He had checked a couple of websites, Michelin UK and one said Porsche 997 should have both front and rear XL while another said front standard load and rear XL. Which makes no sense. Can you help clear up so I can send him your professional advice? What is your take on his car having SL fronts and XL rears...potentially the issue or not a problem, check elsewhere?
Thank you
03-12-2015, 10:22 AM
#3
Former Vendor
I'm very sorry to be so late to the party on this. We were extremely busy here at the time this came in and I missed it. A PM on the thread would have brought it to my attention.
I always try and match XL tires in front with XL tires in the rear if I can if the manufacturer does not have specific tires for the car. I also try and match correct N ratings where needed, also. There are cases where the correct match (19" PS2 N2 and P-Zero N2 for example) are an XL rear and non XL front. In cases like that the correct match IS XL and non XL....The squirm he experienced could have been from several issues, but it's most likely a case where the new tires had more tread than the other axle. They likely would have been a newer tire as well so tread pliability would have come into play. If one tire is of new tread depth and soft, and matched to another tire (on the other axle) that is of less tread depth and possibly of a harder compound from age....the end result could be unfavorable handling. I'm curious which brand they were, and how much tread difference there likely was between the two pairs of tires.
I always try and match XL tires in front with XL tires in the rear if I can if the manufacturer does not have specific tires for the car. I also try and match correct N ratings where needed, also. There are cases where the correct match (19" PS2 N2 and P-Zero N2 for example) are an XL rear and non XL front. In cases like that the correct match IS XL and non XL....The squirm he experienced could have been from several issues, but it's most likely a case where the new tires had more tread than the other axle. They likely would have been a newer tire as well so tread pliability would have come into play. If one tire is of new tread depth and soft, and matched to another tire (on the other axle) that is of less tread depth and possibly of a harder compound from age....the end result could be unfavorable handling. I'm curious which brand they were, and how much tread difference there likely was between the two pairs of tires.
