Tyres R129 AMG Monoblock style

[inazar]

First post, so please be gentle.

I've just taken ownership of a 300SL (R129) 1991 Model.

Needs a few little things to get it back to it's former glory, bit of paint, bit of upholstery and unfortunately the job of sorting out the wheels.

The car came with a set of AMG Monoblock style split rims. Although they actually looked great, they are replicas. The outer rim was chewed up a bit on 3 of the wheels, so I've had them cut and re-polished and will get the middle section painted up myself.

The question I have from a more technical view is regarding tyres.

The old tyres were probably contributing to the ease of kerb damage, so would it be okay to buy a wider tyre?

Current fitting is 235 40 18 at the front and 265 40 18 at the back. Could I go wider say 245 and 275? I'm not keen on dropping the profile, I think 40 fills the gap with the height of the motor perfectly well.

Similarly on my daily runner, I have a set of 19 MV4 rims on a BMW (sorry). The standard fitment is 225 35 19 at the front and 255 30 19 at the back. Can I INCREASE the profile, or does that affect the speedo?

Any technical advice would be appreciated!

 

[RichardF]

To avoid rim damage either.
a) Standard wheel 16" with 225/55 tyre.
b) Take care parking.

You should aim to keep the rolling circumference similar to std, with the same front to back.

Online Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit

 

[BTB 500]

What are the rim widths? You can check what the tyre sizes should be here:

Mercedes-Benz Fitting Chart and Wheel Fitment Guide | Alloy Wheels Direct

235/40 front 265/40 rear isn't a listed combo.

The 18" AMGs on mine (8.5" wide front, 10" wide rear) use 245/40 and 275/35.

The other point is that some tyres nowadays have rim protection ... a ridge that sticks out and will hit kerbs etc. before the wheel does. It's not perfect but it definitely helps prevent minor scrapes. E.g.

https://www.tyreleader.co.uk/tyres-advices/tyre-with-rim-protection

I use this type of tyre on my SL.

 

[inazar]

What are the rim widths? You can check what the tyre sizes should be here:

Mercedes-Benz Fitting Chart and Wheel Fitment Guide | Alloy Wheels Direct

235/40 front 265/40 rear isn't a listed combo.

The 18" AMGs on mine (8.5" wide front, 10" wide rear) use 245/40 and 275/35.

The other point is that some tyres nowadays have rim protection ... a ridge that sticks out and will hit kerbs etc. before the wheel does. It's not perfect but it definitely helps prevent minor scrapes. E.g.

https://www.tyreleader.co.uk/tyres-advices/tyre-with-rim-protection

I use this type of tyre on my SL.

Cheers for that link.

As a bit of a noob :fail, I just went by the tyre on the car. But given that the polished edge was so chewed up, I should've figured it would need a wider tyre.

I imagine even the replicas would be based on the fitment of the originals, so whoever put these old tyres on must've been drunk or found a cheap deal and thought sod it.

On the quoted sizes in my OP, I was quoted four P Zeros fitted for £400. There goes that dream

 

[RichardF]

Cheers for that link.

.

I imagine even the replicas would be based on the fitment of the originals,

Never assume.

The width will be embossed on the rim, you may have to remove the wheel to find it. My replicars were 7.5J, MB would be 8.25J on 17" rims. Not a problem if the offset is ok and the appropriate tyre size is used.

Mercedes SL Class Alloys (R129) - Alloy Wheels Direct

http://www.tyresizecalculator.com/tyre-wheel-calculators/tyre-size-for-rim-size-width-calculator

Any given wheel width will have a range of suitable tyre sizes. The bigger wheel and tyre combos MB use require the arch's rolling to avoid rubbing. A bad idea IMO, makes them even more of a dirt trap than they already are.

 

[BTB 500]

Yup check the actual size and go from there. Often you can find the details on the back of the wheel using a small inspection mirror and a torch.

 

[DanMorgan]

I've ran 275/35/18 - 245/40/18 and 265/35/18 - 235/40/18 profiles and current run the latter.

Personal preference and cost but im runner slightly thinner tyres as I plan to slightly lower the car in the future

 

[demetrios]

Was wondering if I could get wider tyres on my SL.
265/35 r18 rears at the mo on 18" AMG wheels.

 

[inazar]

Went with 245/40/18 and 275/40/18.

Will have pics once bodywork has had a tidy up on a couple of corners.

Due to the lathe cut on the outer rim of the wheels, I had to go wider, curb rash scares me and any protection will do.

Hopefully they fit on just nicely and aren't too thick.

 

[RichardF]

Ideally you'll want 10J on the back and 9J on the front. 9.5J all round would be okay though.

 

[RichardF]

Hopefully you'll be ok, but check the cruise control tyres are on.