@zagaone , a higher load rating will help somewhat for reasons that are a combo of what @Greg W and @JakiChan both allude to.
While it's air pressure that ultimately supports the car, one simply can't increase pressure to prevent bent rims. The relative load and stress strength of the tire's sidewall construction -- including the bead, sidewall profile, and belt-ply construction architecture, among other things -- keep the tire 'together' and functioning when a sharp impact is encountered. A lower load rating is basically a clue that the tire construction factors above are of a lower consideration in the tire's overall design than things such as cornering pliability and road 'feel'.
Thing is, 20-inch rims are not ultimately made for handling. They're made for looks. It's been proven again and again that beyond a certain point, larger-diameter rims with lower-profile tires actually adversely affect handling, to the point where to survive on less-than-perfect pavement, the tire that fits on such a rim has to be designed to handle less well to still be viable for consumer use.
Even so, design can only do so much. For example: tires with an over stiff sidewall can bend rims, too. This is a serial issue with BMWs, many of which come with RFTs (run-flat tires) as standard, even though those tires never perform nearly as well in key ways as traditional tires. So simply stiffening the sidewall isn't an ideal solution, either.
Assuming you'll keep the 20-inchers, I feel your best solution is threefold:
- Find a set with as high a load rating as possible,
- Maintain tire pressures on the higher end of the tire's suggestions, and
- Ignore N0 spec as a prerequisite. Porsche has basically said that the only key difference between an N0-spec tire and a standard-issue tire is wet-weather traction at speeds over 100 MPH.
If the problem persists -- as much a function of driving environment as anything -- I would strongly encourage that you either downsize to 19-inch rims or upgrade to forged wheels.
Hope this helps.
While it's air pressure that ultimately supports the car, one simply can't increase pressure to prevent bent rims. The relative load and stress strength of the tire's sidewall construction -- including the bead, sidewall profile, and belt-ply construction architecture, among other things -- keep the tire 'together' and functioning when a sharp impact is encountered. A lower load rating is basically a clue that the tire construction factors above are of a lower consideration in the tire's overall design than things such as cornering pliability and road 'feel'.
Thing is, 20-inch rims are not ultimately made for handling. They're made for looks. It's been proven again and again that beyond a certain point, larger-diameter rims with lower-profile tires actually adversely affect handling, to the point where to survive on less-than-perfect pavement, the tire that fits on such a rim has to be designed to handle less well to still be viable for consumer use.
Even so, design can only do so much. For example: tires with an over stiff sidewall can bend rims, too. This is a serial issue with BMWs, many of which come with RFTs (run-flat tires) as standard, even though those tires never perform nearly as well in key ways as traditional tires. So simply stiffening the sidewall isn't an ideal solution, either.
Assuming you'll keep the 20-inchers, I feel your best solution is threefold:
- Find a set with as high a load rating as possible,
- Maintain tire pressures on the higher end of the tire's suggestions, and
- Ignore N0 spec as a prerequisite. Porsche has basically said that the only key difference between an N0-spec tire and a standard-issue tire is wet-weather traction at speeds over 100 MPH.
If the problem persists -- as much a function of driving environment as anything -- I would strongly encourage that you either downsize to 19-inch rims or upgrade to forged wheels.
Hope this helps.
