Transporter

The stock size is 245/40/18
The wheel is Style 123
The car is a 2006 530i sport package (I think this matters for clearing)

can I go

225/45/18?
215/45/18?
225/55/18?

Sorry is this was answered somewhere else, could not find it with the search...

Thanks in advance

GregBrand

I have 275 x 40 on the rear with spacers and 245 x 45 on the fronts. Can't imagine getting anything taller without more modifications. Good luck.

edkwok99

What is your offset?
Do you have a picture of it?

Macadee

Useful link for comparisons : Tire Size Calculator

tooltec

The general recommendation is to stay within 3% of the original diameter.Your first two sizes are within the 3% but your 225/55/18 is not.
With a sport package I would not go to a higher profile,only a lower one.

luigi524td

I can imagine circumstances when you would want to move away from lower-profile tires (bad roads, poor weather conditions, etc).

Aspect ratio and rolling radius are two factors to be alert to. Those will affect your speedometer accuracy and fitment within the wheel-well as well as proper clearance of suspension and other gear under the car. The tires must be fitted to wheels of the proper width, too. You must also ensure that the load capacity of the tire is equal to or greater than the tires originally installed on your car. Under-tiring your car can be as detrimental as over-tiring it!

My advice would be to collect opinions on this forum [the tire-size comparison website is helpful] and locate a tire installer / dealer with the expertise to properly help you execute on your plan.

GregBrand

Ed- I don't know my offset but I am running factory staggered 128s if that helps. This is the Pilot Sport A/S Plus -the Ultra High Performance All-Season tire member of Michelin's Pilot family of low profile, high-speed tires that represents the evolution of the Pilot Sport A/S.

Diamond

The 530 sport in 06 assuming you have stock 123's are 245/40/18 like you say. The rims are all 8 inches. Go to tirerack and look at the profile of any tire and you can see what is the sizes that will fit an 8 inch rim. Usually it is 235-255-8-8.5 inch rim
255-275-9 to9.5 inch rim and so forth.

Each time you subtract 10mm from the tire width you have to lower the aspect ratio (sidewall height middle numb) you have to increase by 5 to keep the basic same rolling radius.

By the way your ET are 20 on all for corners stock.

So if you want taller tires for the 245. You need to go 245-45-18. The lowest width with 8 inch rims is 225 so if you wanted 225/50/18 would be the same rolling radius as 245/40/18.

GregBrand

I didn't mind changing my rolling radius since it caused my speedometer to be nearly perfectly accurate. At 75 mph on the speedometer I show, using police radar, that I am actually going 75. With the factory stocks, when my speedometer showed 75 I was actually going 72.

Transporter

Thanks for the great info!

With the 1010tires.com calculator http://www.1010tires.com/tiresizecalculator.asp
and the specs tab for the tires that come up in tiretack.com I am now able to really narrow this down.

It looks like a 215/45/18 fits barely on the stock 123s , since it has a rim range of 7"-8" and the 123s are 8" if I am not mistaken.



Interestingly, From the three tires I mentioned above this tire 215/45/18 matches almost identically to a 245/40/18 (based on 1010tires.com)