gjm 3258 Report post Posted August 24, 2017 I have a set of 8J & 9Jx16 rims that I'd like to use. In order to maintain (closely) factory rolling diameter, I'd like to run a 245/50-16 tyre on the wider rear rims. Looking at various pages it is suggested that this size tyre should be used on a rim from 7 to 8.5 inches wide. (Narrower than my rim .) A 245/45-16 is claimed to be typically fine on an 8 to 9.5" rim. As the profile height goes up, the recommended rim width for fitment comes down - a 245/70 should be fitted to a rim between 6.5 and 8" in width. Back in the old days we used to calculate the optimum tyre width as being rim width (in inches) multiplied by 25, plus 'a little bit'. Hardly scientific, but it worked reasonably well. Modern tyre construction means there have been many changes; for example, the tyre pressure for a given car recommended by the car manufacturer back in 1985 may not be as relevant now as it was then - good modern tyres typically run at higher pressures. The question is... Would I run into problems using a 245/50 tyre on a 9" rim? I could run a 255/50-16 (OK on a 9" rim according to the LVVTA, but still not OK according to several online calculators) but they are (literally) twice the price of a 245-wide tyre. Having resolved this little conundrum, I need to consider what size to run on the front, too... Quote Share this post Link to post Share on other sites
zero 1162 Report post Posted August 25, 2017 On what car? Quote Share this post Link to post Share on other sites
gjm 3258 Report post Posted August 25, 2017 1 minute ago, zero said: On what car? Shouldn't matter, but these are for the 500SE. Quote Share this post Link to post Share on other sites
allan 295 Report post Posted August 25, 2017 Have you had a play with this site http://www.rimsntires.com/specspro.jsp lets you mess with the rim size, off set and tyre size then gives you weather it is a safe set up or not Quote Share this post Link to post Share on other sites
Herbmiester 928 Report post Posted August 27, 2017 The 9 inch style 350s on my car run a 275 width from the factory. Quote Share this post Link to post Share on other sites
gjm 3258 Report post Posted August 27, 2017 (edited) 14 minutes ago, Herbmiester said: The 9 inch style 350s on my car run a 275 width from the factory. I've come to the conclusion that retaining the rolling diameter is going to mean going to a wider tyre... Why do they have to cost twice as much for a width increase of just 10mm? Oh well - safety first. And I'm sure they'll look great. Edited August 27, 2017 by gjm Quote Share this post Link to post Share on other sites
qube 3570 Report post Posted August 27, 2017 dont need to go to an odd size graham. just stick with a more common size Quote Share this post Link to post Share on other sites
