Aspect ratio/height of sidewall (2nd number) ques?

[Nick1994]

Discount Tire shows 2 tire sizes as stock

225/75-15

235/70-15

So 225/75-15 is OEM.

 

[gallydif]

Originally Posted By: WishIhadatruck
I have a '96 Roadmaster Wagon which came originally with 225/75R15 tires. They are very difficult to find and what you do find is nothing special. For my winter tires I run Blizzak's in size 235/75R15, they fit fine and work fine. They might rub just a little more than the original sized tires did. The originals rubbed on the fronts when turning very sharp also.

In the summer I run 235/65R17 tires on aftermarket rims. They are about the same diameter as the 235/75R15 tires. If you like what is available in the 235/75R15 size, go for it.

I bet when you clicked on this thread you didn't think it would have to do with another RM lol. What are the chances- there's only a few of us left. You've actually ran 235/75/15 on it and it's been fine which makes me feel more comfortable. And tell me about it- finding oem tires for this car are a pain in the who know what.


Originally Posted By: Rolla07
http://www.1010tires.com/Tools/Tire-Size-Calculator

This will give you the best answer.


Thank you! States to stay within 3% of the diameter of the original tire, any more than that and you are risking brake failure.
235/70/15, 235/75/15 comparison:
overall diameter: 27.95in, 28.88in
sidewall height: 6.48in, 6.94in
radius: 13.98in, 14.44in
circumference: 87.82in, 90.72in

The diameter variance is 3.31% which is above there recommended percentage. Uhoh

 

[gallydif]

Originally Posted By: Nick1994
Discount Tire shows 2 tire sizes as stock

225/75-15

235/70-15

So 225/75-15 is OEM.

Yes, that is because 225/75/15 is oem for the wagon while 235/70/15 is oem for the collectors edition sedan (mine) and limited collectors edition sedan.

 

[ryanschillinger]

Just get a matching pair per axle, or set of 4 preferably. At $75/each, I would go with the Hankooks and sell your existing 3 good tires on craigslist to offset the cost. Then you have 4 new, matching tires. I see those with 235/75-15 all the time. At least when you actually see them on the road still. Those are cool cars. Love the boat type of ride! I really doubt you'll have any problems with a pair of 235/70 and another pair of 235/75, but can't guarantee that.

 

[GaleHawkins]

I like going with OEM tire size on the door post when using stock wheels but 20 years later it sounds like the 235 75 15 may be the best option. My guess at 55 MPH you will be doing about 58 MPH with the 75's.

 

[SHOZ]

Here's a good site for visualizing different sized tires on the rims and it gives the speedo error too.

http://www.rimsntires.com/specspro.jsp

 

[SwampSurvivor]

Originally Posted By: Nick1994
Discount Tire shows 2 tire sizes as stock

225/75-15

235/70-15

So 225/75-15 is OEM.


That came with bigger tires than my Jeep

 

[gallydif]

Thanks guys. Ended up getting 5 tires for $302. Hankook h724 white sidewalls 235/75/15. Gave in to the 75's. Hopefully it works out. My other tires had more than plenty of tread left but had some dry rot from being old. Decided to shell out the money. These should last me 10 years hopefully.

$100 off $400+
http://www.bobistheoilguy.com/forums/ubb...ds_#Post4027716

 

[Traction]

At least will ride smoother. A lot of trucks use a 75 series with no problem, and the Roadmaster is almost as big as a 1/2 ton truck.

 

[gallydif]

Originally Posted By: Traction
At least will ride smoother. A lot of trucks use a 75 series with no problem, and the Roadmaster is almost as big as a 1/2 ton truck.

Lol. And it has the same engine as the impala ss. The LT1