Inconstant tire sizing between brands? Why wont a smaller tire fit?

[ba82]

To eliminate the obvious questions, here the brief "back story."

In November I needed winter tires and went from a 285/60/18 to a 255/55/18 winter tire. The 285's were worn out when they came off and so I am now in the market for new summer tires.

I have tried two sizes, both 265/65/18 smaller than the 285/60/18's that came off (there were on for 3+ years with no issues or rubbing) and the tire shop I went to told me that both sizes WONT work - they are adamant that they rub and will NOT work.

The first tire that I tried was a Bridgestone Dueler AT RH-S in 265/65/18. When they told me that it didn't fit because it was rubbing, I figgured the 65 was too tall, and went with a BFG Rugged Terrain (265/65/18 & 265/60/18). If a 285/60/18 fit, I figured that the 265/60/18 would fit. Wrong again according to the Tire shop. Tire Size Calculators that I can see online disagree and say they should fit, as dose common logic.

It doosent make any sense to me, and I can only come up with three possibilities:

1. Tire sizes are not consistent between brands and the Fierce ST that I took off was not actually a 285/60/18.

2. The 285/60/18 Fierce ST had a "Performance Street" type of tread (pattern and height?) and the new tires I am trying to put on are AT tires with different Deeper tread. Everything that have read is telling me that this should NOT affect the size that will fit onto the car - a 265/60/18 is the same height and width no matter what type of tread is on the tire - the tread is considered in the size and the size is from the tallest and widest point on the tire.

3. The shop's tire changer is not competent, and is jumping to the conclusion that the new tires don't fit because when the tire tech pulls off the stock size (255/55/18) winter tires, and sees how much bigger the new tire is, they immediately think that I am an idiot BMW owner trying to do something that wont work (I live in Vermont, and here a BMW may as well be a Lambo. If you drive a BMW, everyone assumes you are a millionaire yuppie snob; and treats you accordingly. Its stupid because my X5 isn't worth as much as most of their newer Subarus and Toyotas; and I do all my own maintance! Sorry for the rant......dfferent subject for a different time )

What is the tallest size tire my 2001 3.0 will fit? Any and all opinions are welcome! Please help!

[weekend camper]

This thread might be good reading, until a resident expert pipes up:

http://www.xoutpost.com/bmw-sav-foru...nt-alloys.html

[TwinsPoppa]

Bottom line: If you had 285/60-18s prior and you're not changing wheel specs then a smaller diameter and/or width tire will obviously fit. Just double check those two tires specs and compare them to make sure.

Depending on how different they are from stock size tries, your speedometer may be off.

[TriX5]

265/65 is a good bit taller than 255/55 but roughly equal to 285/60. The OD would 31.5' as opposed to the OE 29". Make sure you have same size on all corners to avoid trouble with the TC.

More stress on your drive train and possibly a bit close on the rubbing issue. You need to find a more helpfull tire shop....

[tmv]

#3. Just tell them to do it.

[JWMich]

OP needs a different tire shop. 275/60 18 fits. No rubbing, no issues. Everything is fine. Smaller diameter or less width will fit without problems, too - that's fact.

Tire shops can be unwilling to sell or install something that deviates from manufacturer specs. If they do it and you don't like it, you'll be back wanting them to take back the tires and redo the install for free. The rework and return, sticking them with four tires that aren't new any more, costs them more money than your work is worth. So they tell you it won't work to save them themselves the potential problem.

What's needed is an indy that will do what you want and won't give you crap. Look for locals, and think about ordering from TireRack and using one of their installers, with a call beforehand to talk about what you want them to do. I've been successful doing that. I've also sometimes used a local mechanic that's done work on my cars for many years.

[ba82]

Thanks for everyone's feedback - Looks like #3 is the winner.

In addition to #3, does anyone feel that question #2 carries ANY possibility of validity? I want to be sure before I order something online.....

Thanks again.

[motordavid]

Yes to #2, imo...every brand and species of tire(s) within that brand, in a given 'standard' size, may vary in tread width, overall height, and rolling circumference; not much, but yes they can vary, slightly.