Does higher profile tyres mean different tyre pressure ?
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Does higher profile tyres mean different tyre pressure ?
I recently changed my tires from 275/30/20 to 275/35/30 rears AND 245/35/20 to 245/40/20 fronts .. This is on a CLS 53 2020.
1- Does this mean a different tire pressure from the MB recommendation of 42 psi front and 41 psi on the rear ?
2- Any insight on acceleration drop % or seconds ?
Thanks much ..
1- Does this mean a different tire pressure from the MB recommendation of 42 psi front and 41 psi on the rear ?
2- Any insight on acceleration drop % or seconds ?
Thanks much ..
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Joined: Nov 2018
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From: San Francisco Bay Area
2019 C63CS
The height of the sidewall does not determine what tire pressure to use. The load rating of the tire does. Every tire has a load rating and a max tire pressure. The load rating indicates how much load a tire can carry when inflated to the max tire pressure on the sidewall, typically that's around 50 psi. That is usually much higher than needed for a particular vehicle. The amount of load a tire can carry decreases with tire pressure, so the recommended tire pressure is set such that at this pressure the tire holds the necessary load with enough headroom. If your new tires have the same load rating as your previous tires, then you don't have to change the tire pressure, but if the load rating is different, then you do.
As for affects on your speedometer etc, here's a good calculator that lets you figure that out. Use the Tire Comparison tab to compare your old tires to the new ones.
https://tiresize.com/calculator/
As for affects on your speedometer etc, here's a good calculator that lets you figure that out. Use the Tire Comparison tab to compare your old tires to the new ones.
https://tiresize.com/calculator/
Last edited by superswiss; Oct 22, 2024 at 03:17 PM.
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The height of the sidewall does not determine what tire pressure to use. The load rating of the tire does. Every tire has a load rating and a max tire pressure. The load rating indicates how much load a tire can carry when inflated to the max tire pressure on the sidewall, typically that's around 50 psi. That is usually much higher than needed for a particular vehicle. The amount of load a tire can carry decreases with tire pressure, so the recommended tire pressure is set such that at this pressure the tire holds the necessary load with enough headroom. If your new tires have the same load rating as your previous tires, then you don't have to change the tire pressure, but if the load rating is different, then you do.
As for affects on your speedometer etc, here's a good calculator that lets you figure that out. Use the Tire Comparison tab to compare your old tires to the new ones.
https://tiresize.com/calculator/
As for affects on your speedometer etc, here's a good calculator that lets you figure that out. Use the Tire Comparison tab to compare your old tires to the new ones.
https://tiresize.com/calculator/
no effect on acceleration so far ..
ur thoughts ?
Appreciate it
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And while we’re at it, here’s the new load rating vs the old, with OEM pressure:
Old 245/35/20 95Y 42 psi - new 245/40/20 99Y ?? Psi
Old 275/30/20 97Y 41 psi - new 275/35/20 102Y ??psi
so what do u recommend as a new psi ?
Old 245/35/20 95Y 42 psi - new 245/40/20 99Y ?? Psi
Old 275/30/20 97Y 41 psi - new 275/35/20 102Y ??psi
so what do u recommend as a new psi ?
Out Of Control!!
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From: San Francisco Bay Area
2019 C63CS
What was the objective to go with a higher aspect ratio? Your speedometer is now reading low. The new tires have a 3-4% larger diameter. That's not necessarily a big deal. The new tires have a slightly higher load rating, so you could technically lower the tire pressures about 10-15%. If you want taller sidewalls for more comfort, you should instead downsize your wheels to 19" with the corresponding tire setup.
Last edited by superswiss; Oct 23, 2024 at 01:48 PM.
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What was the objective to go with a higher aspect ratio? Your speedometer is now reading low. The new tires have a 3-4% larger diameter. That's not necessarily a big deal. The new tires have a slightly higher load rating, so you could technically lower the tire pressures about 10-15%. If you want taller sidewalls for more comfort, you should instead downsize your wheels to 19" with the corresponding tire setup.
Out Of Control!!
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From: San Francisco Bay Area
2019 C63CS
Well it was primarily for a smoother ride .. roads in Cairo are not the best and frequently had dents in the rims .. so when the time came it was time to go for slightly higher tires for better comfort hoping not to lose the smoothness, stability and perfect cornering abilities of the low profile sporty Yokohamas .. I chose the Pilot super sport Michelin in front and the Pilot sport 4s in the back .. did I make the right decision ? Not sure if it’s any smoother ! I don’t really care about speedometer slips it’s minor anyway .. And I wasn’t ready to go for 19’s on this car profile they needed bigger wheels ..
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Well, you also mixed tires. I'm not familiar with the Yokohamas, but the PS4S is one of the best riding and handling performance tires. The Super Sport doesn't ride as well. My '19 C63S Coupe came with the Super Sports, and because I had the PS4S on my prior car, the Super Sport were a noticeable step back and didn't like them. It's also not recommended to use different tires on the front and rear. I replaced the Super Sport with the PS4S same size and the ride as well as the handling is way better. You probably would have been better off to use the PS4S all-around in the correct size.
much appreciated .. and will keep the Tyre pressure then ..
all the best
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