Thanks for all replies

I have a 84 300d, I found nice michelins at sams that are 195/75 R14. The stock tire is 195/70 R14. Would it pose any significant problem to put the 75 series tire on the car or should I find a 195/70 that i am happy with?

I am leaning toward getting 195/70 but i realy like the tread pattern and price of the sams club tire

happy driving

bob

There is a thread on the "Wheels & Tires" forum that outlines the calculation for tire sizes.

Basically, the 75 (or 70) is the percentage of the sidewall diameter in relation to the width of the tire. So for a 195mm width, a 195/75/14 tire has a sidewall height of 195*0.75=146.25mm, vs 195*0.70=136.5mm sidewall height. That's about a 10mm difference.

Add that to the wheel diameter, and you can figure out how much more tread perimeter the 195/75/14 is to the stock size.

Basically, you have a larger tire, and therefore, your speedometer readings will be a bit on the slow side. I didn't go through the entire calculation, but I would guess you would be off by 2 or 3mph when going 60 of more.

I go through this a lot with the Beetle. I am always having to figure out a new tire profile to purchase, as the current profile gets discontinued...

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

The difference between 70 and 75 profile tires is not great. The 75s should fit just about anywhere a 70 would. That is just the ratio between side wall height and tread width. The lower the number the lower the profile.

This is what is referred to as "Aspect Ratio" of a
tire.

Bob,
Try the two sites listed below for your tire sizing. Between the two you'll be able to get a pretty accurate idea about the effects of changing tire size from the original. Good luck.
John CH

http://www.powerdog.com/tiresize.cgi
http://www.miata.net/garage/tirecalc.html

Thank you for your replies

So other than the MPH effect there is no real negative factor that would keep from buying those higher profile tires. I dont drive very aggressively so I wont miss the Handling all that much. I like the treadwear on that michelin because it is the closest tread to a snow tire that i have seen on an allseason tire yet. It has alot of sipes. So I may buy them after all

Thanks again.

When i buy them i will post to tell all what i think about them.

bob

You could possible try a 205/65 or a 215/65, it may have the same overall diameter as your factory setup. I put lager width tires with a mumerically lower aspect ratio on my 190 and the diameter was the same. The larger diameter tires may affect your accelleration slightly, but may give you better highway gas mileage.

__________________
1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T

I have driven 123 cars about 700,000 miles total, plus my wife probably went another 200,000 or so in them. So, I've been through MANY tires on them.

The difference in the 195/70 and 195/75 is about 3% in diameter, meaning only a 3% speedometer error, which means when your speedometer says 60, you'll really be doing about 61.8, not a big deal. To calculate diameter:

first number/25.4 x aspect ratio x 2 + wheel diameter

example 195/25.4 x .75 x 2 + 14 = 25.515
195/25.4 x .70 x 2 + 14 = 24.748

24.748 / 25.515 = .9699 or 3% difference

My best tire for these cars is a 195/75 Michelin XH. The 75 series tires are considered "passenger car" tires and are a harder compound. This means they last longer. Michelin tires are ROUND, not square like many other tires. If these cars were stiff suspended sports cars, a 75 series would probably not be what you want, but they are not. They are reasonably well handling sedans, and the 75 works great.

If you want a hair better handling and are willing to see many less miles out of your tires, then the 70, or even a 205/60(which I have run before) is what you want. If you want reliable, smooth running, long lasting tires, put on 75 series tires.

My $0.02,

Thanks for the replies

I feel real comfortable with purchasing the 75 series tire as my driving style is not very aggressive. I do enjoy having a safe car that will handle and responde in a favoralble mannor when needed. I do appreciate that I can put a 215/65 on there as reported by JDUB. I am considering Yokohama avid at that size.

I will probably go with the Michelins now that I have finally have a car that is worthy of them.

have a good weekend

bob

the difference between 75's and 70's is not a big deal.

Seeing as you own a 123, your speedo is probably registering faster than you're really going anyway, so getting 75's may actually help.

-Larry

__________________
It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

The price difference between the 75's and 70's is NOT what makes the 75's more economical. The 75 series tires are termed PASSENGER CAR tires and have a harder compound than most 70's. There are exceptions to all rules, but typically the 75's will last considerably longer. I have put MANY tires on 123's and 75 series Michelins is the way to go, believe me.

One other thing, on the 123 cars it is particularly important to see that the tire store puts weights on the inside AND the outside of the wheel. I learned this a long time ago, and have had tense moments with tire stores over this. Most of them have a tendency to put weights ONLY on the inside because it won't look good on the alloy wheels to have weights. Believe me on this, ENSURE that they balance them with weights on both the inside AND outside.

I have had them put weights only on the inside even after I make a big deal out of this issue as a condition of buying their tires.

Good luck,