Car is extremely unstable with new tires. Cause?
10-12-07, 11:50 PM
#1
Car is extremely unstable with new tires. Cause?
I just got some new tires. They're 275/35-18. My rear rim size is 9.5". The previous set of tires I had were 265/35-18. I bumped up a size for increased traction but the car is now extremely unstable at high speeds. I almost got in a wreck yesterday. At first I thought the tire pressure could be the culprit. The tire shop set it at 35psi. I raised it to 45psi to match my front tires to see if that would fix the instability. The problem is still there so tire pressure is ruled out. Basically it feels as if the rear of the car is trailing the front by a split second. For example, I jerk the wheel to switch lanes fast and the front of the car starts going over but the rear lags a split second before it starts moving over. It kinda feels like I'm towing a trailer. I put on my spare set of G35 rims in the back for now and that's solved my stability problems 100%. The car now moves in unison instead of like a pulling trailer.
So the big question is...could the 10mm bump up in tire width cause this? Or could it be an alignment issue? Keep in mind I had no problem when running the 265/35-18 and the G35 rims have 245/45-18 with no problems either. Also, I'm not using cheap crap tires either. I never cheap out on tires. The tires that were on the rims before were Bridgestone Potenza S02 and the set I have on are Potenza RE050. The G35 wheels have BFG KDW2 tires. I'm gonna take my car to get an alignment tomorrow to see if that will cure this problem. If not, expect to see two nearly new Potenza RE050 275/35-18 tires with less than 20 miles up for sale here. I'd really hate to have to pull the tires off and buy new ones...but if worse comes to worst I'll just have to do it.
So the big question is...could the 10mm bump up in tire width cause this? Or could it be an alignment issue? Keep in mind I had no problem when running the 265/35-18 and the G35 rims have 245/45-18 with no problems either. Also, I'm not using cheap crap tires either. I never cheap out on tires. The tires that were on the rims before were Bridgestone Potenza S02 and the set I have on are Potenza RE050. The G35 wheels have BFG KDW2 tires. I'm gonna take my car to get an alignment tomorrow to see if that will cure this problem. If not, expect to see two nearly new Potenza RE050 275/35-18 tires with less than 20 miles up for sale here. I'd really hate to have to pull the tires off and buy new ones...but if worse comes to worst I'll just have to do it.
10-13-07, 05:59 AM
#3
jeff you are cool bro
what you are exper is called tread block squirm .. also there is a chemical added to all new rubber to preserve them while on the shelves , that also must me scrubbed off by driving , the tires are new i assume correct?? with the larger contact patch the squirm becomes more pronounced.. give it about 100-200 miles let the trad blocks settle in and u will see a big diff in handling
trust me been there done that and btw 45 is too much air even in front .. u are not allowing the tires to do there job at that pressure for when they get hot your prssure is actually almost 50psi
bring your fronts down to 40 and the rears down to 38-39 and give it alittle time to settle in
what you are exper is called tread block squirm .. also there is a chemical added to all new rubber to preserve them while on the shelves , that also must me scrubbed off by driving , the tires are new i assume correct?? with the larger contact patch the squirm becomes more pronounced.. give it about 100-200 miles let the trad blocks settle in and u will see a big diff in handling
trust me been there done that and btw 45 is too much air even in front .. u are not allowing the tires to do there job at that pressure for when they get hot your prssure is actually almost 50psi
bring your fronts down to 40 and the rears down to 38-39 and give it alittle time to settle in
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