Rims

[Ahsan Javed]

Hi, 

Can I put 8j (front) and 8.5J (Rear) rims on bmw f10 (SE) without spacers? If they can be fitted then what should be the perfect tyre size for them? 

Can you help please? 

Regards, 

Ahsan. 

[Greydog]

Hi Ashan

Welcome to the Forum

First a question, are the rims you have brought BMW or Aftermarket ? You also dont say what size 17" !8" 19" 20" all were available for your car.

8j front fitment should have an offset of 33ET stamped on the inside of the rim, 81/2j should be 33ET 9j would be 44ET 

Tyres lets assume 19" rims 8j front 81/2j rear with the correct offset Front would be 245/40R19 94Y Rear 274/35 R19 98Y

The offset is important to ensure the rim is centred on the hub to maintain the geometry

Hope that helps

Dave

 

[Ahsan Javed]

Hi Dave, 

Thank you for your reply mate. I was looking to buy 18x8J and 18x8.5j, so I was concerned if they fit well on the wheel base. I am not looking for the bigger size tyre (245/40R19 94Y Rear 274/35 R19 98Y) as they affect the consumption of the car. I'm thinking to put 225/50/18R front and 255/45/18R rear. At moment, my car has 225/55/17R (both front and rear) so I was thinking of I get these combinations then it won't effect much on the consumption. 

What do you think? 

Regards, 

Ahsan. 

[Greydog]

Hi Ahsan

If that is what you want that choice it will work fine

As for consumption that depends on several things (1) the rolling résistance of the rubber compound the tyre is made from (2) Tyre pressures (3) Mechanical condition of the Suspension and brakes 

When choosing tyres you will see a consumption/fuel rating so look for the one with the best figure 

Dave

[Ahsan Javed]

Hi Dave, 

Thanks for assisting me on this. I really appreciate that. My last question, if I get A rated tyres then do you think my suggested tyre sizes (225/50/18R front and 255/45/18R rear) would be a good combination? 

Regards, 

Ahsan. 

[Greydog]

Morning Ahsan

Tyre types are chosen for many reasons, Cost, Looks, Grip, How long they last? For many just because "that was what it came with"

Tyre profile has 2 effects (1) lower profile (side wall) tyres are stiffer offering less sideways movement so give better handling. Down side the ride can be harder, crashing over every imperfection on the road due to less compliance. (2) A higher profile sidewall tyre will be more compliant and help with ride comfort.

Tyre ratings for economy run from A the highest to G the worst. I did read a report a couple of years ago that the difference between the best and worst was about 7.5% so if you get say 30mpg on an A rated tyre you will get around 28mpg with a G rated tyre. That is the theory but as said before the condition of Brakes, Suspension and the pressure in the tyres all have an effect.

The same report also noted that 70% of cars sampled had at least 1 underinflated tyre which will undo any A rated choice. 

So your choice is fine, will look right and will give a good compromise between ride and handling, Tyre pressures should be checked regularly (I do mine weekly while checking oil and water) if you keep the tyre pressures correct you should give yourself the best chance of achieving good mpg and the best tyre life. To many car drivers today rely solely on the car to "tell them" if the oil is low, coolant is low, or tyres under inflated. 

Dave

[Ahsan Javed]

Good afternoon Dave, 

That's a great addition in my knowledge. Thank you very much for your help. 

Much appreciated.

Regards, 

Ahsan.