When tires become old, suspension becomes stiff!
That’s exactly what I started feeling while driving my Mercedes-Benz 180 ponton. The first thing that came to my mind was a problem with the shock absorbers, with some rubber pieces, some bearings…etc. Careful examination of the car's underneath showed absolutely no defects!
Then, came to my mind the tires! I have installed new old stock 6.40-13 radial tires back in 2002! I had not changed them since! They looked good but were in fact full of hairline cracks! Time to change them!
What size should I put? A question that’s easy to answer for modern cars but extremely tough for old ones! Ideally new 6.40-13 shall be installed! Basically, these tires are not in production anymore!!! Automatically one needs to start looking for the best replacement!
Thorough research, especially on www.mbzponton.org, led me to the following conclusions:
1- The sizes of tires are not expressed in inches anymore, but in cm
2- The 6.40-13 means, a section width measuring 6.40 inches and a 13inches rim
3- The best equivalent modern size is the 175/80R13 or the 185/80R13
In modern terms, what do these numbers mean?
The 175 or 185 is the section width size expressed in cm. The 80 is the aspect ratio, in other terms it means that the height of the tire (from the rim to the tread) is 80% of the section width size. Finally, the 13 is in inches and it designates the rim size.
Now came the toughest part! I need to find these sizes!
Asking all the local tire shops in my area led to no results vis-à-vis the 175/80R13! Michelin proposed to order them from France at an extremely high price! The closest available were the 165/80R13. I believed they would look thin and short on the car.
On the other hand, relatively better results showed up regarding the 185/80R13. Only the Maxxis dealer had this size. A quick search on the internet showed very good reviews on this brand in general.
To my surprise, the Maxxis tires had a white wall! Now I faced a new dilemma: Should I install the white wall inwards, thus making it invisible, or install it outwards? Another night of thinking and reviewing photos made me decide to install it outwards!
Quickly, I installed the 4 new tires and drove the car! Not only the suspension became smoother, but the general handling improved drastically, add to it that the white walls gave the car an amazing classy appearance!
My car has new shoes! In four years I'll hopefully change them and order the 175/80R13 Michelin- my favorite brand of tires!