Help - Firestones on Front - Michelins on Rear

[Don Lindeman]

Looking for a little longer treadwear, I recently replaced my rear Firestone Firehawk run-flats on my stock-wheeled '99 C5 with a pair of Michelin Pilot Sport A/S ZPs. The tread on the front Firestones is only only about 1/2 gone, and I thought I'd try running them down a little further before I replaced them too. I immediatley noticed a handling issue in that the car seems slower to react to steering input, and just seems really "squirrley" in general. My "butt feel" is that the new Pilot Sports on the rear seem to have more sidewall or sipe flex than the Firehawks. This may be due to the new tread being a lot deeper than the old Firehawks which were just starting to show the wear indicators. There has been a lot of favorable reviews about the Pilot Sports which prompted me to try them this time around. Since I don't have any experience with the Pilot Sports, can somebody tell me if my problem will go away if I replace the front Firehawks with new Pilot Sports? I don't want to spend more money on additional Pilot Sports, if that isn't going to fix the problem. Thanks,

[duesouth]

ask luke

[Luke@tirerack]

while you are experiencing the feel of ...... more tread depth = more tread block flex ...

and all season tires like the Michelin has smaller tread blocks which also flex more than the larger blocks found on summer tires

you are also experiencing all-season tire vs. summer performance tire ..... all season tires have more flex than summer tires do .... that's primarily due to the rubber compound maintaining flexibility in the cold ....

the car will feel more balanced with new Pilots on the front but it will never feel as planted as the Firehawks did

[Don Lindeman]

Thanks Luke.... Guess I should have done a little more research and paid attention to what I signed up for.

I was on my 2nd set of Firehawks since I replaced my OEM Goodyear EMTS at about 18K on the car through Tire Rack, and really liked everything about the Firehawks except the mileage. Only getting about 18-20K on the rears, and 30K on the fronts (Which was just about the same as the Goodyears).

I did have a concern about the Firehawks however. When my first rears were removed from the rims at about 40K on the car, there was about a 6-inch crack on the inside of both of the tires where the sidewall meets the inside bottom of the tire. I chalked it up to poor removal technique, and decided to put on another pair because I really liked the way the Firehawks performed. Well this time around (58K on the car), the same type of crack was visible on the left-rear when it was removed. This particular tire did pick up a nail about 5K ago and I had it repaired from the inside. According to my tire pressure monitor, the tire only got down to about 25psi before I had it repaired, and it did not go completely flat.

I guess my choices are:

1. Try and trade back the Michelin Pilot Sport M/Ss ZPs for non-M/S ZPs on the rear, keep the front Firehawks until they run out, and then get non-M/S Michelins on the front.
2. Try and trade back the Michelin Pilot Sport M/Ss ZPs for non-M/S ZPs on the rear, get new non-M/S Michelins on the front now.
3. Get M/Ss now on the front to replace the Firehawks.
4. Replace the new M/Ss with new Firehawks on the rear, and be wondering about the cracks being a safety issue.

What a delemma

Considering that I was happy with the Firehawks, but am now a little concerned about the cracks, and I am not happy with the handling of the Pilot Sort M/S Zps compared to the Firehawks, can you help me sort this out?

Thanks again,
Don

[Luke@tirerack]

the only problem is that there isn't a non-M&S ZP Michelin

[Don Lindeman]

Oh....

Well that certainly limits my options. Have you heard about anyone else experiencing the cracks in the Firehawks?