i plan on lowering my c280 on 17x7.5 front and 18x8 in the back. what tire size is good? i already have 245/40/17 for the front and was considering 235/45/18 for the rear? what do you guys think and is it too much tire for the rear??
1) 245 up front may be too wide for a lowered car without modifications to the fender (depends on offsets as well). Did you check the tool in the Sitcky? It will give you a better idea of clearance, especially in the front.
2) Different wheel size? Whats going on there?
3) Your real wheels will be skinnier than your fronts? You have a rear wheel drive car, a wider stance out back will give you better traction. I have run 255 and 245 in the rear. I have seen others go to 265.
Yeah 17s in front and 18s in back. Only using different sizes because I got them seperatley for a really good deal. I plan on getting 18s for the front when I get the chance. But for now that's how its going to be. Also I'm using 45s up front because that's what it came with. Hopefully it doesn't rub. I didn't check the tool because I didnt know the stock offset for 280. Do you happen to know?Originally Posted by Denlasoul
Looks like 15x7 ET 37 for stock wheels. You could always pop off the wheel and check.
The 17s I'm putting on the front are et35 and rear 31. And now that I think about it wouldn't make any sense to put 40s In the rear considering IMA put 45s in front. What's your take on the two different rim sizes. What's would be the cons of having 17s in front and 18 in rear?
The overall diameter of the 17s wheel is 24.7 inches. The overall diameter of the 18s wheel in 26.3 inches. In order to match the wheel rotation properly, you have to get equivalent rolling diameters, ie both front and wheel diameter is the same regardless of the wheel size. To do so, you would have to play with the tire sizes. Im not too good with that, but maybe someone can chime in.
Not sure about performance cons and such, but I would think your speedometer would be thrown off.
edit: for my 18" wheels I run 225/40/18 and 255/35/18 and 17" wheels I run 225/45/17 and 245/40/17.
so to keep the over all diameter i would have to have smaller sidewall tires on the front or bigger?
if you're using 17s up front and 18s at the back then keep both diameters the same... but why do that? imho just have the same size wheels up front and at the rears... get the perfect set and then switch... it'll be better off when you rotate tires... assuming that you plan to do that...
when i had 17s i had 225/45/17s... i am running now on 225/40/18s..
i deffinetley plan on getting the same size in the near future, maybe by the end of this upcoming summer, but im running on a budget so im trying to work with what i have. and when you say keep both diameters the same you mean keep them both at 45s for the tires?
No. A 45 series tire on an 18" wheel is much different than a 45 series tire on a 17" wheel.
for example: tires that is 255/45/18 = 27" total diameter
tires that is 255/45/17 = 26" total diameter
difference of 1"
try this website: http://tire-size-conversion.com/tire-size-calculator/
You will want to have your 17" wheels and tire diamter as close as possible to your 18" wheel and tire.
some basics: 255/45/18 means that the tire is 255mm wide, the 45 means that the sidewall is 45% the width (255 x .45) and the 18 is your wheel size.
to calculate overall diameter: 255 x .45 = 114.75mm
114.75mm = 11.475cm
there are 2.54cm in an inch, so 11.475/2.54= 4.51 inches of sidewall
so, 18" wheel + 4.51" sidewall + 4.51" sidewall = 27.02" overall diameter
Conclusion: you will either have to raise the series size in the 17" tires or lower the series of the 18" tires. Keep in mind it is not just going to next series, you will have to play around with different combinations to achieve almost equal overall diameter of both your 17" and 18" wheels.
These cars really do not need that wide a tire up front. Rear traction is more of an issue the way the roll axis canters as well as combined narrow tall chassis. I run a 215-40-18 up front and a 245-35- 18 out back Front is a 24.8 tall, rear is also 24.8. The front tread on the ground is 8.4" the rear 9.2" on the footprints.
My rim widths are 8.5 front and 9.5 rears. You have 7.5 fronts- that 245 is way too wide and will reduce turning response from slop.
You really should run a 225-45-17 / 235-40-18 to have a good matched set with appropriate sidewall height proportions and bulges.
Anything else would not look right, nor really work anywhere as well performance wise. The fronts are 25" tall, the rears are 25.4" tall
if you guys want a good wheel calculator then use this tool:
http://www.rimsntires.com/specspro.jsp
Thankyou. I was just about to sit here and calculate the correct dimensions I would need. You all helped a lotThese cars really do not need that wide a tire up front. Rear traction is more of an issue the way the roll axis canters as well as combined narrow tall chassis. I run a 215-40-18 up front and a 245-35- 18 out back Front is a 24.8 tall, rear is also 24.8. The front tread on the ground is 8.4" the rear 9.2" on the footprints.
My rim widths are 8.5 front and 9.5 rears. You have 7.5 fronts- that 245 is way too wide and will reduce turning response from slop.
You really should run a 225-45-17 / 235-40-18 to have a good matched set with appropriate sidewall height proportions and bulges.
Anything else would not look right, nor really work anywhere as well performance wise. The fronts are 25" tall, the rears are 25.4" tall
if you guys want a good wheel calculator then use this tool:
http://www.rimsntires.com/specspro.jsp
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