[Benzacream]

I have a w204 c250 with OEM 17" staggered wheels (staggered in the sense that only the rim width of front and rear wheels are different).
The sport also has a slightly lower front suspension.

Even still, the 245/45/17 tires fit fine all around with no rubbing.

There is a slightly noticeable sidewall bulge on the front (due to the narrower rims in the front that are 17"x7.5" vs 17"x8.5" in the back).

I like it as it fits the wheel wells better, and I got them for cheap and it works. Where I am, I need the extra clearance to avoid scrapes and obstacles.

OEM 225/45/17 front-- 25.0" tall
OEM 245/40/17 back-- 24.7" tall
245/45/17 are 25.7" tall

If I were to do it again (and eventually will when these long-life 540 utqg tires wear out), I would go with 235/50/17 in front (26.25" tall) and 255/45/17 (26.0") in back to make the look more uniform (sidewall bulge), wider rear tire look, get another 1/4" clearance in front, and fit the wheel well tighter (I am almost certain this will work for me when I checked clearance to suspension components (upper control arm) and fender well liner, etc, but I personally have not tried them yet, so beware for fitment issues). It is just a lot harder to find those tire sizes that are not super expensive, don't wear out fast, and a matching set/brand. The fronts are easy to find but the 255/45/17 are about 50% more in price and have short tread life as they are more race-oriented. I am not a fan of buying new tires every 18 months.

 

[GT3 guy]

That’s going to throw off your speedo and the 235/255 are 2 wide for the wheel width... imo... but to each their own

 

[Benzacream]

That’s going to throw off your speedo and the 235/255 are 2 wide for the wheel width... imo... but to each their own

I would normally agree with you EXCEPT that the speedo originally said I was going 1mph too fast before the tire change. Now it says I am going 1 mph slower than actual speed as measured by GPS at 50mph. A lot of cars, from the factory, say that the vehicle is going faster than actual speed, including BMW and Lexus (from my experience) but that is really on a case-by-case basis, and should be judged by actual GPS measurements.

Factory front wheels are 225/45/17...going to 235mm width (the smallest increase in width available wider) is not too wide for 17x7.5" wide wheels as it is well within accepted range. After all, I have 245/45/17 on right now...that is the upper limit. On top of that, the higher the section height of a tire, the "more" forgiving the accepted wheel ranges become.

Given that 245/40/17 is factory for the 17x8.5" rear wheels, the barely wider but taller 255/45/17 is a miniscule difference. In fact, 255/45/17 tires generally have an accepted wheel width range of 8.0"-9.5"...my 8.5" is right in the middle.
The wheel width range limit for the current front 245/45/17 are 7.5-9.0"...the OEM 17x7.5" on the c250 sport are 7.5"...the limit, but completely acceptable.

235/50/17 accepted wheel width range 6.5-8.5 (OEM 17x7.5 front is right in the middle)
255/45/17 accepted wheel width range 8-9.5" (OEM 17x8.5 rear is close to the middle also)

I am more concerned about rubbing, which I don't get (even at high speed turns) except minor rub going over parking lot speed bumps at 5mph or more. The slight increase in overall height (0.35"/ 1/3 of an inch) helps me clear the bad potholes a little better as well as scrapes/catching on the front bumper fairing. Even the 235/50/17 replacing factory/OEM 225/45/17 on the front would only increase overall height 0.64" overall/ 2/3 of an inch over factory. The C250 sport already has a more pronounced forward rake (front suspension lowered more than the luxury models), so changes are not very pronounced.

 

[GT3 guy]

And why are you wanting different sized tyres?

 

[prktkljokr]

great tool for working out tyre difference and spedo accuracy

Tire Size Calculator

The best tire size calculator. Use our tire size calculator to find tire size specs and suggested tire sizes. Then check prices for all available tire sizes.

tiresize.com

 

[Benzacream]

And why are you wanting different sized tyres?

The w204 C250 Sport comes with 225/45/17 tires on 17"x7.5" rims from the factory (OEM) on the front.
The rear wheels are 1" wider (17"x8.5") and come with 245/40/17 tires from the factory.

I needed slightly taller tires where I am to avoid scraping all over on the bottom and front fairing/bumper.
Yes, you can put the same tires on all 4 wheels, but then there will be a wider sidewall bulge on the front wheels compared to the back because the front wheels are narrower.

245/45/17 works as I have demonstrated. Surprised no one else reports on this or if 235/50/17 works on the front and 255/45/17 on the back.

 

[Gazwould]

245 is too wide for the 7.5 fronts , 235 is the limit .

Absolutely bang on to actually measure before and after real world GPS , because the tyre & wheel calculators can't account for tyres that aren't produced to the stated sidewall width and aspect ratio .

Between different makes can be quite a difference !

 

[Benzacream]

245 is too wide for the 7.5 fronts , 235 is the limit .

Absolutely bang on to actually measure before and after real world GPS , because the tyre & wheel calculators can't account for tyres that aren't produced to the stated sidewall width and aspect ratio .

Between different makes can be quite a difference !

My c250's speedo always said I was going faster than gps or even police speedos so the slightly taller tires were ok in this situation.

A speedo calculator confirms the speedo change...going from 245/40/17 to 245/45/17 @50mph would have an actual speed of 51.95mph...2mph difference. Since my speedo was fast 1mph before, it worked out perfect to be just 1mph slow now @50mph.

As for 245/45/17 on the 17x7.5" rim being too wide, it is within range for recommended tire/wheel width size.
However, if the tires were 245/40/17 with shorter sidewall on the front then, yes, they would be too wide for 17x7.5". The taller 45- sidewall makes it a little more forgiving to accept a wider rim width range. Don't have to take my word for it, I just confirmed this on a couple of websites on recommended rim widths for a certain tire size and also the manufacturer rating for my specific tires. Super low profile 25- 35- tires are the opposite and can usually accept wheels only 1" apart on the high and low wheel width range, while Tall truck tires can typically accept up to a 5" wheel width range (ie, 7"-12" wide for some 35" tires).

On my next set, I will probably do 235/50/17 front and 255/45/17 back to better fit the staggered wheels...raise car 0.6" vs stock (really not that much overall but helps for my needs) but fill the wheel wells better for the sport look.

 

[Gazwould]

As for 245/45/17 on the 17x7.5" rim being too wide, it is within range for recommended tire/wheel width size.

Incorrect..too wide .

 

[Benzacream]

Incorrect..too wide .

Hey, I appreciate other information and different views, but you are incorrect on this one.
The first clue should be that the rim size chart you quoted doesn't take into account the "section height", but only takes the one-dimensional tire section width measurement.

So here's mine:
Not only do the websites all say the generic tire size 245/45/17 accepts a 7.5" rim, but even specific manufacturer tire data on every tire I selected show they accept a 7.5" rim. For the Mercedes stock rear tire size of 245/40/17, you would be correct that 8.0" is the minimum rim width. But I have 245/45/17, slightly taller section height.

https://www.tirerack.com/tires/tire...SAS3PLXL&vehicleSearch=false&fromCompare1=yes (Excerpt from the "Specs" Tab)

http://www.etmags.com/pdf_download_documents/tire_chart_2010.pdf (excerpt)
tire size / rim width range (inches) / section width on rim width

https://www.discounttiredirect.com/buy-tires/milestar-ms932-sport/p/19341 (excerpt)

I agree if someone tried to put OEM 245/40/17 on the front 17"x7.5" rims, there would be a problem as the minimum width is 17"x8" for that tire size. The shorter section height gives these tires a less forgiving wheel width range. To be clear, they probably would fit, but if they didn't get the air pressure just right, they could slip off the bead in a corner or if flat...big liability. My Taller 245/45/17 tires are "MADE" for 17"x7.5" rims up to 17"x9.5" rims as their recommended range, there should be no debate about this.

 

[Gazwould]

One of us is wrong and one of us is right , and I know who it is...

I personally run and have run an OE manufacture size 235 45 17 on 7.5J for six years and my father also on his old car .

On his new car we didn't like his 225 45 18 , so upon renewal went 245 40 18 on the 8J .


So what do you think of tyres not being produced to the width and aspect ratio sizes on the sidewall ?

 

[Benzacream]

Are you saying 245/45/17 are not acceptable/recommended for 17"x7.5" rims? This is easy to remedy. Go to tirerack.com and look up 245/45/17 tire size, then click on a few and go to the "specs" section to see manufacturer recommended wheel width.

Don't trust tirerack? No problem. Better yet, go to the manufacturer website for Continental's, Pirelli and Bridgestone and do the same thing. I did, and they all say the same thing that 245/45/17 fit 17x7.5 wheels fine. Do you not trust the manufacturer specs?

I do agree that many tires have different overall dimensions, some run slightly larger/smaller/narrower (even from the same manufacturer as 2 Continentals below show). Sometimes the tread shoulder geometry is different to lead to different overall width of the tread while some have fat sidewall bulges and some have nearly no bulge. This variation even from same manufacturer is found between all-season/touring tires that have larger sidewall bulges versus high performance/summer/race tires.

17"x7.5" rims are acceptable for "nearly" (or possibly) all 245/45/17.
245/40/17 require 17"x8"

Mercedes Benz offers no less than 13 tires as replacements for w204 c250's, 3 from Continental, 4 from Michelin, 2 from Yokohama, 2 from Bridgestone, etc. Some are runflats, summer sport, etc

Not all of these tire models are offered in 245/45/17 as I used instead of the OEM 245/40/17. But of all that do, here is the manufacturer specs from their respective websites and every single case says 245/45/17 can be used with 17"x7.5".

Michelin Pilot Sport 4S
https://www.tirerack.com/tires/tire...tireModel=Pilot+Sport+4S&partnum=445YR7PS4SXL

All of the specs below are direct from the manufacturer websites.

These Continental ContiSportContact 5 only require a 7" rim for their 245/45/17. Why? I don't know, but it's the manufacturer's specs from their own website.
ContiSportContact 5 - 245/45R17 95W | Continental

Continental ContiProContact All-Season Touring 245/45/17
ContiProContact - 245/45R17 99H | Continental

Oddly enough, the Michelin MXV4's are offered only in 245/40/17 and 245/50/17, but no 245/45/17. These 245/50/17's also require only a 7" rim at minimum width while the 245/40/17 require an 8" minimum rim width.
Section height does matter, not just section width.
Michelin MXV4 https://www.michelinman.com/tires/pilot/pilot-mxm4.html

Yokohama Advan Sport A/S+ (last column is acceptable rim widths)
ADVAN SPORT A/S+ | Yokohama Tire Corporation

Bridgestone DriveGuard run-flats (last column is acceptable rim widths...very stiff sidewall which is why they only have a 1" acceptable width range)
DriveGuard Run-Flat Tires | Engineered for Peace of Mind

Bridgestone Potenza RE980AS (245/45/17 is on first line while 245/40/17 is on third line--last column shows recommended rim widths)
All-Season Performance Tire | Bridgestone Potenza RE980AS Tire

Always check manufacturer specs first as even between 2 continentals, one can accept a smaller rim even through both are listed the "same exact size". This is usually from different dimensions, elasticity and sidewall molding around the tire width. But as far as 245/45/17's on 17"x7.5" rim, it is not a problem in every manufacturer I've seen. But don't try to put OEM 245/40/17's on the front 17"x7.5" rims...they need an 8" rim width.

 

[Gazwould]

Well that is a strange one , different camps saying different sizes .

We need a 'bible'.

 

[MissMe22]

Incorrect..too wide .

VERY NICE.

 

[Benzacream]

I've run 245/45/17 tires all-around on sport rims (17x7.5 front; 17x8.5 rear) for the past 3 years with ZERO problems...2 sets so far. No strange wear or anything. And I run the car harder than many (not all) on here. So it doesn't do anything weird to the geometry, steering, alignment, etc.
Each individual tire and company shows specs on their website of what wheel size they recommend for each model tire they sell. It varies from manufacturer to manufacturer. You can't just say 245 is too wide, as a company may say so for low 40-profile but say it is acceptable for higher 45-profile. Fills wheel well better for me and just enough lift to reduce getting the front bumper hung up on bad parking spot bumpers that have the rebar stick out.
So, I am not living on the edge waiting for disaster...the tire manufacturer says the 7.5" front wheel is fine for 245/45/17.

 

[GT3 guy]

Q

I've run 245/45/17 tires all-around on sport rims (17x7.5 front; 17x8.5 rear) for the past 3 years with ZERO problems...2 sets so far. No strange wear or anything. And I run the car harder than many (not all) on here. So it doesn't do anything weird to the geometry, steering, alignment, etc.
Each individual tire and company shows specs on their website of what wheel size they recommend for each model tire they sell. It varies from manufacturer to manufacturer. You can't just say 245 is too wide, as a company may say so for low 40-profile but say it is acceptable for higher 45-profile. Fills wheel well better for me and just enough lift to reduce getting the front bumper hung up on bad parking spot bumpers that have the rebar stick out.
So, I am not living on the edge waiting for disaster...the tire manufacturer says the 7.5" front wheel is fine for 245/45/17.

it will work, it’s just not optimum.. it’s still to wide for a 7.5 tho. I didn’t read all the other posts, but the cars came with 225/245 on 7.5/8.5. That should state the obvious.
I went to by Blizzaks for the oems and they basically had 225’s… that was it. 235’s were sold out, no 245 available and 255’s on an 8.5 (uh no) so sadly I had to run that setup 225x4. The rear looked ridiculous. I have seen this setup a few times on various MB… I should got 215’s up front to even out the rears… oh well it’s only for 3 months a year. Just bought new 235/255’s for the summer 18’s.. that should be good