New Tires

[67charger]

Here are some pictures of 255's mounted on our rims...just thought somebody might be interested.
http://members.cox.net/unothedog/magnum/tire1.jpg
http://members.cox.net/unothedog/magnum/tire2.jpg
http://members.cox.net/unothedog/magnum/tire3.jpg
http://members.cox.net/unothedog/magnum/tire4.jpg
http://members.cox.net/unothedog/magnum/tire5.jpg

Let me get some lame excuses out of the way...it's dirty because I just got back from a trip to California (750 miles). I didn't get good front and back shots because I borrowed the camera at work for some quick shots. I'm parked in the handicapped spot because I use a wheel chair (sometimes people ask).

I bought these at Discount Tire in Arizona for $648 out the door. I was going to get the KDWS BFG's, but these were in stock and I have liked every Michelin tire I have ever owned. They have excelent side grip, but I expected more off the line grip. I will try to provide more details as I get more miles on them.

Pilot MXM4http://www.discounttiredirect.com/images/kotspacer.gifLuxury Performance Touring All-Seasonhttp://www.discounttiredirect.com/images/kotspacer.gifhttp://www.discounttiredirect.com/images/kotspacer.gif255/55R-18 104V GM B
Specifications:http://www.discounttiredirect.com/images/kotspacer.gifTreadwear: 300http://www.discounttiredirect.com/images/kotspacer.gifTraction: Ahttp://www.discounttiredirect.com/images/kotspacer.gifTemperature: Ahttp://www.discounttiredirect.com/images/kotspacer.gifSpeed Rating: VR

[Black on Black]

With 300 treadwear, I would expect a AA traction rating. Hmmmm...

[Padre Dave]

At which store in AZ did you purchase those? I am looking for something wider and with a more "aggressive" tread pattern, but those may work as well. Are they pretty quiet? I do lots of highway miles between Tucson and Fountain Hills, where I am serving a church right now.

I have only 7500 miles on the factory Contis now, but am already starting to look for a set of replacement/upgrade tires.

Thanks!

[67charger]

They are more quiet than the Contis, but I was expecting most of the road noise to go away...it didn't. I had 13000 miles on the Contis and they were pretty much shot. These have deeper tread than the contis did when new so I expect they will last longer.

I bought them at Cooper and Warner. I had a print out from the website at $123/tire (not mounted) so they honored that price. He said they were in his system at $180 without doing a competitive price over-ride.

[MAGNUM8R]

They look good, I had those on my Intrepid RT, and they cornered well and lasted 45K miles with some agressive driving. Just a wuffo, 255 is taller or wider?? I need to replace the Conti's soon, 19K Miles, they are toast!

[boggart]

255 designates the width. The 55 is the height of the sidewall as a % of the tire width. I'm not sure what height the orig tire is, but this is likely close to the same height.

[BobF's 6POINT1]

255 is taller and wider.

[67charger]

These are slightly taller...was told .1" by one calculation and .3" by Discount Tire.

[MAGNUM8R]

These are slightly taller...was told .1" by one calculation and .3" by Discount Tire.
.3" taller? Heck, It could burn that off in a week (LOL)
Anyone have the specs on how far that throws off the speedo??
I am really thinking about the Toyo tires also.

[Old Navy]

.3" shorter tire will be about 1.75% speedo error or about one mph fast at 70 mph true.

[SoCalRT]

The stock 225-60-18 is 28.62 inches tall and the 255-55-18 is 29.04 inches tall a diameter difference of 1.45% taller. The speedometer variance would be 1.466% too slow with the 255's.

So at 60mph on the stock tires and 60mph on the speedo with the new tires the actual speed would be 59.1 mph.

I found this handy calculator on a few different tire sites.
http://www.1010tires.com/TireSizeCalculator.asp

Most of the sites recommend keeping within 3% of the stock tire diameter.

[Old Navy]

Well my first estimate was 1.5, but who cares it was just quick in my head figuring. Anyway like I said your speedo will be about 1 mph fast.

And to think I just barely made it through college algebra. :wink:

[Dupie24]

SoCal,
Thanks for the link to the tire size calculator, way cool 8) Now I know that my Toyo 255/45/20 is prett close to stock diameter, my speedo is only 1 mph slow. Very cool web site, thanks :grin:

[Diesel]

i had the BFG's installed today 245/55, and they have more of a buldge to the sidewall now than the stock Conti's... (understandable)...

so i'm assuming yours are even moreso buldged... not to mention the sidewalls are even taller than the stock counterpart...

i guess if you actually do a lot of driving this is good, as you'll have more cushion... for me, it was a looks thing as well as ride comfort though...

[67charger]

i had the BFG's installed today 245/55, and they have more of a buldge to the sidewall now than the stock Conti's... (understandable)...

so i'm assuming yours are even moreso buldged... not to mention the sidewalls are even taller than the stock counterpart...

i guess if you actually do a lot of driving this is good, as you'll have more cushion... for me, it was a looks thing as well as ride comfort though...

How do they look in comparison to the photo's at the start of the thread? I was worried about 'crowning' but, Discount Tire assured me they would not crown. I wish the stock rims were just a little bit wider. They do ride nice...I'll have to keep an eye on how they wear.

[EHUPP01]

I think your speedo would indicate slow not fast because you are traveling a greater distance per rotation of the tire since its diameter is larger. So when you show 60 you would be traveling 60.9 I think really it don't matter because I dont think our speedo's are that accurate anyway.

[DavidA]

I have the Michelin Pilots on my T-Bird. The car came with them and I bought another set and whitewalled them. I've got about 30K on the set now and they still look great. I'd say the wet traction is not as good as it once was, but the wear bars are still a long way off. One of these days, I'll put back on the original set, (still blackwalls), and try to wear them out. I think I'll switch to these soon on my RT. I thought I'd wait until the Charger came out as I understand it is going to come with Michelins rather than Continentals.

[Old Navy]

I think your speedo would indicate slow not fast because you are traveling a greater distance per rotation of the tire since its diameter is larger. So when you show 60 you would be traveling 60.9 I think really it don't matter because I dont think our speedo's are that accurate anyway.
The larger the wheel/cog without changing the opposing gear slows down the opposing gear and vise versa. If you go to smaller tire, the rpms increase for that tire and as a result the the speedo gear or sensor is making more rpm and that results in speedo reading faster.

Modern speedometers are really quit accurate, as both my Magnum & VW was within 2 mph at 70 mph or within a 3% error margin or less.

[DaddyO]

Is this the Max Meat you can put on a stock RT rim with no adverse effects or Modifications?

[Black on Black]

<255mm wide is about right. Every tire is different, so check the specs. They will tell you the rim width range that the tire is capable of being mounted to. Most 255mm 18" tires will have a range of 7.5-9.0, for instance.Is this the Max Meat you can put on a stock RT rim with no adverse effects or Modifications?

[DaddyO]

You know what I'm thinking? I would like to get the biggest fattest meats that fit on the stock rear wheels and just use up the stock Contis on the front.

[67charger]

I think 255 is about as fat as you want to go with the stock rim. My fronts cup and the rears lose tread depth so quickly I would hate to lose the ability to rotate.