Bottoming Out

[clean1scene]

I have a 1982 300D. My problem is that when I drive through sharp dips at speeds over 40 MPH, the car bottoms out and the tire rubs the fender well. The tires on the car are P215/70R15's. The recommended size, posted on the door post, is 195/70SR14. If I went back to the recommended size, would this eliminate the tire rubbing? The rest of the time the car rides real smooth.

[sixto]

What's the offset of the 15" wheels? The right offset will keep the 215s from rubbing. I know 205s work in a 300D with no rubbing.

Bottoming has nothing to do with the wheels and tires.

Sixto
95 S420
87 300SDL

[clean1scene]

Originally Posted by sixto

What's the offset of the 15" wheels? The right offset will keep the 215s from rubbing. I know 205s work in a 300D with no rubbing.

Bottoming has nothing to do with the wheels and tires.

Sixto
95 S420
87 300SDL

Thanks for your reply. I am sorry, but when it comes to tires, wheels and suspensions I have very little knowledge. What do you mean by offset? Also I want to clarify my situation. The suspension doesn't bottom out, the front tires, especially the drivers side, hit the fender lips when I go too fast through a sharply angled dip. The rest of the time the car handles real well, one of the smoothest riding vehicles that I have ever had.

P.S. The rims are Mercedes rims, if this helps.

[t walgamuth]

to the distance between the center of the tire measured looking forward from the center point between the front and back wheel on either side and the mounting point of the wheel to the hub. if the hub coincides with the center of the tire and wheel that is referred to as zero offset. the newer wheels place the tire closer to the car i believe.

are your wheels mercedes?

the previous poster believes that your wheels and tires are mounted too close to the outside of the fender and thus are hitting on dips. i believe that is what he said.

tom w

[clean1scene]

Originally Posted by t walgamuth

to the distance between the center of the tire measured looking forward from the center point between the front and back wheel on either side and the mounting point of the wheel to the hub. if the hub coincides with the center of the tire and wheel that is referred to as zero offset. the newer wheels place the tire closer to the car i believe.

are your wheels mercedes?

the previous poster believes that your wheels and tires are mounted too close to the outside of the fender and thus are hitting on dips. i believe that is what he said.

tom w

Thank you for the definition. To answer your question, yes my wheels are Mercedes.

[Brian Carlton]

215-70-15's are a huge tire for a W123.

I ran 215-70-14's on it for awhile and they looked quite big. This is two sizes larger than stock. Now, you are also going up one size on the wheel diameter. This raises the height of the tire significantly.

You are hitting the fenders because the offset might be too low. However, with this huge setup, you may not be able to increase the offset much because the wheel will hit the tierods.

You can check to see how much clearance you currently have to the tierod. I'll bet it's less than 3/8". This would be difficult to safely reduce my much.

Check the existing wheels for the offset, as Sixto explained above. There will be the letters "ET" followed by a number such as "25". The offset of those wheels is 25 mm.

Are the tires hitting the inside of the fenderwells at the top, or is the fenderwell lip digging into the sidewall?

[t walgamuth]

brain is right. those tires are prob just too tall! wide too.

tom w

I agree, these tires are huge for a 300D. Monster truck huge.

I use 205/70-14s which are about 2% over stock, these are 8.5% over stock. The diameter is more than 2 inches larger than stock. It appears that 215/60-15 would be closer to the original diameter, but I don't know if the width would fit.

[t walgamuth]

big tires look macho i suppose but i have always regretted it when i have gone bigger than stock. the steering is crisper and the ride and handling is better with stock. if you are gong for a big number on a skidpad a big wide stticky tire is good but in real world driving i like to use what the car was designed for.

tom w

[haasman]

I would also recommend going back to the stock, OEM, tire size. You will get MUCH better fuel economy, faster acceleration and overall better handling.

Haasman

[clean1scene]

Originally Posted by Brian Carlton

215-70-15's are a huge tire for a W123.

I ran 215-70-14's on it for awhile and they looked quite big. This is two sizes larger than stock. Now, you are also going up one size on the wheel diameter. This raises the height of the tire significantly.

You are hitting the fenders because the offset might be too low. However, with this huge setup, you may not be able to increase the offset much because the wheel will hit the tierods.

You can check to see how much clearance you currently have to the tierod. I'll bet it's less than 3/8". This would be difficult to safely reduce my much.

Check the existing wheels for the offset, as Sixto explained above. There will be the letters "ET" followed by a number such as "25". The offset of those wheels is 25 mm.

Are the tires hitting the inside of the fenderwells at the top, or is the fenderwell lip digging into the sidewall?

To answer your question, the fenderwell lip is digging into the sidewall.

I would like to thank everyone for their response. This tire/wheel setup was already on the car when I bought it. As soon as I find genuine Mercedes wheels I am planning on going back to 14"'s.

I am glad that I came across this forum, you folks are wonderful. Have a GREAT DAY!

[Brian Carlton]

Originally Posted by clean1scene

To answer your question, the fenderwell lip is digging into the sidewall.

I would like to thank everyone for their response. This tire/wheel setup was already on the car when I bought it. As soon as I find genuine Mercedes wheels I am planning on going back to 14"'s.

I am glad that I came across this forum, you folks are wonderful. Have a GREAT DAY!

If you like the 15" wheels, there is nothing wrong with keeping them. I'll bet that 205-65-15 tires will work like a charm.

Did you check for the offset on the existing wheels like I asked?

[clean1scene]

Originally Posted by Brian Carlton

If you like the 15" wheels, there is nothing wrong with keeping them. I'll bet that 205-65-15 tires will work like a charm.

Did you check for the offset on the existing wheels like I asked?

No, I haven't checked yet. Where do I find the letters "ET" and number?

[sixto]

On the back or non facing side of the wheel. You'll have to scrub off years of brake dust to see the numbers.

Sixto
95 S420
87 300SDL