Road Force balance or replace rear Bilsteins or ???
Race Director
Joined: Jan 2005
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From: Slidell Louisiana
Found out the wheels have 1/2oz weights, so cut what I said in half. And, that's only on the 11" rears. (Probably more necessary for the chromed factory wheels than the tires too)
It always easy to blame cheap.
After going to my buddy's Chevy shop, I found out the problem(s). In this case, the tires spin balance correctly, but Road Force did show 2 of the four can't be road forced balanced. This does result in some mild vibration (when not on smooth hiway).
This wasn't my only issue.
Because I have a cammed motor -- connected to a sidepipes -- connected to the frame, that's the other issue. The sidepipes are isolated [from the frame] with large rubber bushings but the cam (and my hot low rpm timing) can cause some "cam surge" that transmits thru the exhaust piping and therefore, the frame. When going 70+ on rough hwy -- in 6th gear, the combination can be annoying. I just wanted to make sure it wasn't problematic. (And, luckily, the problem rpm range is very narrow.)
I think the addition of the flex pipe (sections) in my exhaust might solve most of the problem.
If I ever convert to an HSR and start running 100mph, then I'll consider $1000 tires and dumping the sidepipes.
It always easy to blame cheap.
After going to my buddy's Chevy shop, I found out the problem(s). In this case, the tires spin balance correctly, but Road Force did show 2 of the four can't be road forced balanced. This does result in some mild vibration (when not on smooth hiway).
This wasn't my only issue.
Because I have a cammed motor -- connected to a sidepipes -- connected to the frame, that's the other issue. The sidepipes are isolated [from the frame] with large rubber bushings but the cam (and my hot low rpm timing) can cause some "cam surge" that transmits thru the exhaust piping and therefore, the frame. When going 70+ on rough hwy -- in 6th gear, the combination can be annoying. I just wanted to make sure it wasn't problematic. (And, luckily, the problem rpm range is very narrow.)
I think the addition of the flex pipe (sections) in my exhaust might solve most of the problem.
If I ever convert to an HSR and start running 100mph, then I'll consider $1000 tires and dumping the sidepipes.
Thread Starter
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From: Overland Park Kansas
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They're both a tire issue. Two are very good and two aren't. What ever it means, two are less than 8 (oz's or lbs?) of road force, while the other two are in the mid 30's. The printouts say "the wheels are good but the tires can't be put in any orientation to negate "road force imbalance". I guess that means there QC is 50% of Sumi's? It'll be interesting to hear what the vendor's have to say about it. (BTW..It's my understanding that road force imbalance has to do with a radial/tangential forces and nothing to do with lateral imbalance/wobble.)
Since they're fine up to 70mph, it might be an issue where they let "borderline" tires thru...because you're not supposed to drive faster than that anyway. I barely feel anything at 70...and it seems the motor connection to the sidepipes may be the bigger issue. And, that even depends on throttle opening.
Since I just bought them, I'll have to accept the way it is (unless it's something covered by manufacturer's warranty). Are Sumi's really a TireRack brand (e.g., made for TRack...Someone told me that this week.)
Since they're fine up to 70mph, it might be an issue where they let "borderline" tires thru...because you're not supposed to drive faster than that anyway. I barely feel anything at 70...and it seems the motor connection to the sidepipes may be the bigger issue. And, that even depends on throttle opening.
Since I just bought them, I'll have to accept the way it is (unless it's something covered by manufacturer's warranty). Are Sumi's really a TireRack brand (e.g., made for TRack...Someone told me that this week.)
Last edited by GREGGPENN; Jul 1, 2012 at 12:51 AM.
Thread Starter
Race Director
Joined: Nov 2003
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Though they are the least expensive 315 at TireRack, they help make an 11" wheel purchase affordable. Plus, they are ranked 16th of 28 tires in their category. They are not ranked worst and have never been considered (by this reader) as crap. Some want fatter tires and some want tires to last longer. Others even want auto-cross performance. I need neither.
My first set wore very evenly and lasted a reasonable amount of time. Plus, they gripped better than the crappy Nitto's I had before the Sumis. As far as wear, they last 4-5yrs with my mileage -- that's how long I want a tire to last. Beyond that, age takes over.
I'd be happy to have you prove the significant issues with imbalance. It will help my "case" when emailing the vendors. I'll also be happy to post about how they can't be trusted to balance out (if we can prove it) -- which is a much bigger issue about tire width, manifested with the usual whining in threads about: "What kind of tire I should buy?".
Last edited by GREGGPENN; Jul 1, 2012 at 03:35 AM. Reason: clarity
Race Director
Joined: Jan 2005
Posts: 10,641
Likes: 13
From: Slidell Louisiana
They're both a tire issue. Two are very good and two aren't. What ever it means, two are less than 8 (oz's or lbs?) of road force, while the other two are in the mid 30's. The printouts say "the wheels are good but the tires can't be put in any orientation to negate "road force imbalance". I guess that means there QC is 50% of Sumi's? It'll be interesting to hear what the vendor's have to say about it. (BTW..It's my understanding that road force imbalance has to do with a radial/tangential forces and nothing to do with lateral imbalance/wobble.)
Since they're fine up to 70mph, it might be an issue where they let "borderline" tires thru...because you're not supposed to drive faster than that anyway. I barely feel anything at 70...and it seems the motor connection to the sidepipes may be the bigger issue. And, that even depends on throttle opening.
Since I just bought them, I'll have to accept the way it is (unless it's something covered by manufacturer's warranty). Are Sumi's really a TireRack brand (e.g., made for TRack...Someone told me that this week.)
Since they're fine up to 70mph, it might be an issue where they let "borderline" tires thru...because you're not supposed to drive faster than that anyway. I barely feel anything at 70...and it seems the motor connection to the sidepipes may be the bigger issue. And, that even depends on throttle opening.
Since I just bought them, I'll have to accept the way it is (unless it's something covered by manufacturer's warranty). Are Sumi's really a TireRack brand (e.g., made for TRack...Someone told me that this week.)
I've had good luck with Goodyear F1 supercar tires and Bridgestone Potenzas. Back in the 1980s I was talked into FALKENS as a replacement for the Michelins on my new Mustang GT.... Bad move, car changed into a wallowing slug on the back roads . I quickly replaced the Falkens with Michelins and swore I'd never bought cheap tires again. Funny thing was this was before the internet and some of my buddies were running Falkens, however, I guess since their cars were older and they never had quality tires on their cars they didn't know any better. Fast forward I bought Kuhmos for my SS since they had good reviews, short story within a month I hit a bridge guardrail in the rain, USAA considered the car totaled. So I will never buy cheap tires again. Damn I loved that SS.
I'd count your thread as another strike against budget parts.
Last edited by aboatguy; Jul 1, 2012 at 03:07 PM.
Burning Brakes
Joined: May 2008
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From: Greensburg PA
People think low cost means junk, that isn't always the case. Sometimes I think vette owners are used to get shafted with pricing, so when something reasonably priced comes along it's usually considered junk.
PLENTY of people sun sumi's, and have positive experiences. I'm not saying it's the stickiest or widest, but it's certainly not junk.
PLENTY of people sun sumi's, and have positive experiences. I'm not saying it's the stickiest or widest, but it's certainly not junk.
Thread Starter
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From: Overland Park Kansas
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People think low cost means junk, that isn't always the case. Sometimes I think vette owners are used to get shafted with pricing, so when something reasonably priced comes along it's usually considered junk.
PLENTY of people sun sumi's, and have positive experiences. I'm not saying it's the stickiest or widest, but it's certainly not junk.
PLENTY of people sun sumi's, and have positive experiences. I'm not saying it's the stickiest or widest, but it's certainly not junk.
I would also point out that I identified the real issue but Mr. Pyschotic want's to blow up his ego. This thread is probably over because of it.
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From: Maryville Tn
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Yes, I believe this thread is run it's course. Take the debates and bickering to PM's. When I have to delete posts, it makes me want to hand out vacations from the forum. Let's agree to disagree and be done with it.
