New tires 245/45ZR18

[BlackIceLSC]

My 98 LSC came with Michelin Pilot sport A/S tires....they were ok...smooth, lasted a long time but are pricey! Even when worn BEYOND the wear bars, they were smooth as silk, and quiet.
it was time for some new ones. I am a service manager at an auto repair shop. I decided to try some Ironman iMove 2 A/S

https://d2gvvn2873sxv5.cloudfront.n...etire/logo.png,0,0,1)/tiregallery/11638/1.jpg



....They are made by Hercules, which is owned in part by American Tire Distributors, one of my leading suppliers.
I got a great deal, so on they went. I developed a huge balancing issue/vibration at 2 speeds: 45 mph I had steering wheel wobble, like a OOR tire. I rebalanced them, and they were barely off. I suspected our balancer was out of calibration so I recalibrated it. Now the vibration changed from 45 to 70-73 mph. Under light acceleration the rear felt off. When coasting, the front felt off. It would come and go, so I suspected it was the car. I rotated them front to rear and nothing changed. I was sure it was the car. Some days there was no vibration....I was perplexed. But knowing I bought cheap tires, I contacted ATD and decided to turn them in and try something else.
I did some research and found tires designed in Finland for "heavy, performance cars"....well, guess what? That's what I drive!

I bought Nokian Z-line tires. Their reviews talked about great wet-weather handling, smooth quiet ride and decent tread life.

https://www.nokiantyres.com/summer-tyres/nokian-zline/


https://www.youtube.com/watch?v=tm-FodKRM0M

I installed them late Friday after work. They balanced out beautifully, with hardly any weight. all wheels are perfectly round, I use hub-centric rings, and properly hand-torqued all lugs. The valve stems were lines up with the wheel lock and the yellow-painted wheel stud on the front. The tires have no movement when spinning on the balancer, nor do the wheels so nothing is OUT OF ROUND.

from 1-68 mph they are hands-down the BEST tire I have ever driven on! At 70-73 mph the vibration is horrible.
I am not sure what else to do at this point. it feels more like driveline related but as we all know, when lifting the vehicle the driveline never changes angle.

I run 245/45R18
wheels are Speedstars with hub-centric rings. Again, the old bald 4 yr old Michelins were smooth.

I suppose I should pay another shop to check/balance the tires for me just in case our balancer is on the fritz but we sold 4 sets of tires yesterday and I test drove the vehicles when they were complete and they were perfect...even a Dodge Ram 2500 with massive 305/70r16 Cooper STT-PRO tires (very heavy and agressive).

Thoughts or suggestions are appreciated as I hate to cause excessive wear to the car. Until then, I'll drive under 70 mph at all times.

The Nokian Z-line tire is AMAZING though....and very inexpensive if you can find them!

 

[Ford nut]

Jason had the same problem, think he had to have them speed balanced I will send him a text and get him to post.

 

[97MarkJA]

I did have the same problem.. twice.
First time was when I bought wheels and tires from the custom wheel shop. 18's.
The hub centric rings were slightly off, one ring of electrical tape cut to end match and they were smooth.
When I went to the 20" godspeeds it was pretty bad from 65-73ish mph.
Took and had them road force balance, they are pretty smooth now. Night and day difference from before.

 

[BlackIceLSC]

can you elaborate on the "one ring of electrical tape cut to end match" statement?

I am completely puzzled. My 18's were fine from the day I bought the car until I bought new tires. The hub-centric rings are snug on the hubs and in the rim pockets.
I need to find a road-force balancer I guess.
Thank you!

 

[Ford nut]

Hub centric rings were loose and he used tape as a shim.
I would try what Jason had to do, I now its frustrating when they wobble at speed.

 

[Slowmkviii]

I have a vibration on my 18s from the coustom wheel shop at least on wheel has a casting problem the back side of the wheel runs out perfectly but the face runs out

Run the wheels on the balancer without tires.

 

[BlackIceLSC]

going to take it to a shop that uses a Run Force and see how it goes.

 

[tixer]

Good luck!

I do like Luke's idea of spinning them without the tire to see what's what. I know my last set of tires took the shop 3 tries to really get right. I had to pull the guy aside and stress that the problem was the vibration (over 80, in my case.. ) He took his time and did it right..

 

[BlackIceLSC]

I checked the wheels without tires. My problem is, there was ZERO vibration when I bought the car...it had used Michelin Pilot Sport A/S on it...2 were 50% worn, 2 were 70% worn....it drove as smooth as it should....as ALL other Mark VIII's I've owned and driven(trust me when I say I've driven a lot of them...even a 93 with 50k, and 20 yr old Michelins...)

the day I installed my new tires, I had a steering wheel shimmy at 45 mph that went away at 50 mph and then a seat AND steering wheel vibration from 65-70 mph.
I re-balanced them, found them off a bit and the 45 mph shimmy went away and the 65-70 changed to 70-74 mph.

I spun them again and watched 2 of the tires have slight up and down movement(not the wheels, the tread area).

Dissatisfied, I decided it was the tires, so I replaced them with the Nokians. Before mouting the new tires I spun just the wheels. They are as true as any alloy I've seen. Washed them clear of any dirt and old weight tape and installed the Nokians.

They took far less weight and had almost zero tread movement. On the car, they were smooth as silk, right until 68 mph.
Here's where it gets hard to decipher:

Under light load(constant throttle) the vibration is in the steering wheel. If I lift/coast, the vibration changes to the floor area. ONLY at 68-72 mph. At 73+, it feels like a perfect car. At 0-67 mph, it feels like a perfect car. The KICKER is: if the road is bumpy or has those perpendicular lines across the lane, the vibration is subtle.

I talked to my Hunter rep, and he stated that the Road Force balancer will find the problem because that is EXACTLY what it was designed for...changes in load and force.

Now Here's where I am frustrated: the local Les Schwab Tire shop with a Road Force balancer wants $100 to do all 4 tires. I aint a cheap-o but I'll be frustrated if I pay that and they cant find any problems.

I've never run in to this before. Then again, I've never had 18" wheels on a Mark VIII before(EDIT: when I bought Scott Miller's old 95, it had the 18" Bullitts on it, and they shook like mad at 65+ and I was told they were impossible to balance).
. It's just odd that the old, bald, 5 yr old tires were vibration-free.

My hub-centric rings are tight in the wheel bore and on the hub.

 

[tonybrooklyn]

If you must have 18's and 100 cures the problem.
Small price to pay for what you want IMHO.
Good Luck whatever you decide.

 

[BlackIceLSC]

well it came with the 18's. I wasnt a fan of the silver but like I said, they came with it. I have a set of Octastars I could put on it but it sits so nice with the 18's I just wish they were chrome or polished.
But yea, I know...$100 isnt a mountain of cash...just that I do it for a living(service manager, and also work on cars/tires/wheels) so I know it's a rip. We charge $40 for the same work...I guess *someone* has to pay for that Road Force machine, right?

 

[Slowmkviii]

Sounds like as service manager you should tell the owners you need a road force balancer as another perk to sell customers.

 

[BlackIceLSC]

I wish!...Seriously though...we considered it but we just had to shell out money for a new air compressor AND Hawk-eye alignment machine. There went this year(and next year's) equipment budget!

If it was as easy as "telling the owners", I'd have a company car!
But I get what you're saying.
The earlier comment about "If you must have 18's and 100 cures the problem.
Small price to pay for what you want IMHO."
I have to say I disagree. Running 18's isn't exactly parting the red sea. Many new cars come standard with 18's., so it isn't like it's an unusual set up.
Our cars have had to use Road Force balancers at times since inception even to get a set of stock 16's perfect, so it isn't the wheels...IT'S THE DARN CARS! lol
(finicky things!)
I'll be headed to the tire shop during black Friday when all the other crazy folks are out Christmas shopping, I'll be getting my wheels balanced.
I'll update this thread when it's done.
Thanks for all the input gang.

 

[Mad1stGen]

I've had quite a few sets of those M8 bolt pattern Speedstars go thru my hands, all from that Custom Wheel market place. They all had the same issue you're describing. There is something wrong with the cast IMO. It was worse on chrome finished wheels than painted. The face of the wheel would be ok, but the barrel was always a little out round. It wasn't as noticeable with good tires (i.e. Michelin PSS) but throw any type of chunky junk on there, and they would woble no matter the balancer used. I hub swapped several of those cars to the same wheel but with proper hub sizing and bolt pattern, and problems went away. I agree that the m8 suspension is very sensitive to imbalance, as it seems it was designed for lighter 16" wheels.

Pay now or pay later. Buy better tires next time. It's worth it.

 

[BlackIceLSC]

Thanks Jeremi....you just saved me $100

perhaps I'll find different wheels. Your experience in this matter is gospel to me, as always.

 

[Ford nut]

Never had a set of wheel shop rims, I know Jasons wheels were hub swapped Godspeeds.
I have a set of 18s I bought from Jeremi years ago.

I don't remember who made them, but never had a problem with what ever I stick on there.
I eat rear tires like pop corn so I hit craigslist for what I can find wide enough with the right profile.

I guess your money is better spent on a hub swap.

 

[BlackIceLSC]

I guess your money is better spent on a hub swap.

That wont help as these wheels are drilled for 5-4.25
money better spent would just be new wheels instead of hub swap AND new wheels.
sadly, it rides like an absolute dream from 0-64 mph and 72-"above" mph

I'd consider new wheels or a trade if someone wanted but it's just so odd the Michelins rode perfect. The wheels call for less than 0.5 oz. of weight with no tires on them and have no visible run-out or movement when on the balancer with a straight-edge touching the wheel lip as it spins.

Oh well...they ride a lot better than the old 18" Bullitts I had on my 95.

 

[BlackIceLSC]

I've had quite a few sets of those M8 bolt pattern Speedstars go thru my hands, all from that Custom Wheel market place. They all had the same issue you're describing. There is something wrong with the cast IMO.

For what it's worth, the wheels were purchased from Super Coupe Performance LLC. I have the receipt right here.
"Saleen Speedstar 18x9 - 5x4.25 pattern silver finish, from March 2014. They came with the centering rings and were $170.99 each + freight($90.99).