Jump to content

Bias Tire Conversion and Differences in Size


51_Meadowbrook

Recommended Posts

This may not be the right spot for this post but here goes. It’s time for me to replace the tires on my cars and the old debate pops up. Which tire size should I get? My ‘51 Dodge Meadowbrook originally had 7.10-15 bias tires on it. The guy I bought it from out 225/75/15 on it. So when I changed them I put them on too. As I’m looking at different conversion charts they are saying 215/75/15 or 225/70/15. Being a little green on tires I’m not sure exactly what makes one tire better or worse than the other. I understand the fundamentals of the tire sizes but not necessarily the functional difference between them. Anyone willing to shed some light and their thoughts on this would be great. Does one provide a better comfort when riding down the road than the other?

Link to comment
Share on other sites

one aspect ratio is equal to one width dimension in up and down....215/75 would be equiv to 225/70 IF you are looking at trying to maintain the revs per mile.....the 70/75 is the ratio of the tire sidewall compared to the width of the tread....OF IMPORTANCE.....on a radial the width will roll up and onto the lower edge of the sidewall...many forget this and think that the 225 is the actual on the ground tire patch....NOT....

Link to comment
Share on other sites

The key thing is tire height.  Change that and the speedometer will be off.  Shorter tire makes the speedo read faster and a taller tire makes it read slower.

 

Then there is the load capacity to consider but unless you get really crazy in going small it's usually not an issue but the tires do have to be able to support the GVWR at the pressure you are running. 

  • Like 1
Link to comment
Share on other sites

I run g78 bias about 10,000 miles a year with no issues. That's even hauling and carrying loads in my 59 F100 with a 223 and 3 speed. If you want a radial, 225/70/15 should be about right. Just figure the taller the tire, less bottom end you will have but you will have higher cruising speeds. Tire size will come down to how and where you drive. If you just cruise around town and do short trips, you can get away with a shorter tire. If you are going for distance and higher speeds, go with a taller tire.

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.

Terms of Use