Is My Wheel/Tire Size Combo Whacked?

[Amanda]

I've got 6 x 7 x 16 Fuchs. The PO put 225/50-16 and 245/50-16 tires, F/R respectively. Anyone see a problem w/this?

[dentist90]

Amanda- your rim sizes appear to be just wide enough for these 50 series tires, but you will get a bit more sidewall flex under cornering as the tires will be "bulging" out from the rims. Lower profile tires ( eg 40, 45 series) are even less tolerant of being tucked into narrower rims and you'll find wider rims are indicated for a tire of the same width. Eg., 205/50/17 accept rims 5.5" to 7.5", while 205/45/17 suggest 6.5" as minimum width rim even though they are same width tire. You may find that the front tires rub your fenders if your car is lowered. Your speedo will show a lower speed than you are actually travelling. Check out this page to see the suggested rim widths for Yoko Tires... Yokohama Rim Sizing

[ZOA NOM]

Yep, they are both too wide for those rims. Well, you could fit the 225's on the 7" rims. The rear tire is too tall, also. It should be 225/50/16. Your speedo will be off by quite a bit with 245/50's.


Here is a tire size calculator that will show comparisons between different sizes, side by side. Pay attention to the overall diameter.

[dentist90]

If you look at Zoanas' avatar you'll get an idea of what can happen if you put too large a tire into too small a rim... like I said, all BULGY!

[Early_S_Man]

Amanda,

Those tires and wheels are within the acceptable range of rim width specs published by the Tire and Rim Manufacturers Association. Unless you are experiencing a handling problem with those tires, don't worry about it! A visit to www.tirerack.com can give you options for future tire purchases ... once a set of tires is displayed for a particular brand, click on the 'SPECS' button to bring up specifications for that entire tire line.

As a side benefit ... since Porsche speedometers are notorious for reading 'optomistic,' or up to 10% higher than actual speed, the net effect of the taller rear tires may be to give a more accurate speedometer reading.

[Amanda]

Can anyone point me to where I can see the acceptable ranges of rim width specs published by the Tire and Rim Manufacturers Association that Early_S_Man mentions?

I'm thinking about keeping the 245/50-16 tires on my rim 7s and maybe getting some 1" spacers. The $$ saved (from not getting 8s or 9s) will go towards other stuff.

[Wavey]

Go to Tire Rack's web site - they have charts by manufacturer and tire size with all the tire dimensions, acceptable rim widths, etc.