[freespirit]

Hi All,

Need advise on 225/45R18 vs 245/40R18 Also RF vs NRF ... i have 2016 328i with M Sport Pkg and Staggered wheel setup.
Front : 225/45R18
Rear : 255/40R18

Today i purchased Michelin Pilot Sport A/S 3 Plus in above mentioned size in discount tire and went for installation. After completing the installation of rear tires, the sales guy called me and said they have some problem in the inventory and could not find the front tires in 225/45 size and said he will install 245/40. In case if i am not satisfied with the handling, he said he will replace them with 225/45.

In the evening i took the car out for a drive and see some issues while cornering. On a 55mph curved ramp i was on 60mph and i feel the front side of the car wobbling badly. I tried multiple ramp at some random speeds and feel the same thing.

Can you guys suggest if the wobbling is due to different tire size or because of Non run flats as it will have softer side walls ?

Thanks & Regards,
Kishore.

[eluded]

Don't they rub? I would ask the Tire people to put the proper size tires on.

You want to run Michelin pilot super sports or greater.

[Soul_Glo]

Yes it can cause wobble and handling problems. Due to the tyres he put on your speedo is out by 1 per cent - not a big deal. However, you have lost more than 3mm on wheel arch gap with a bigger tyre. This in turn impacts on the front geometry. Your options are get the original tyre size intended or get a full geometry done i.e. alignment, camber and, toe adjustment.

It's nothing dangerous it just means your car won't handle as intended and you won't enjoy it. Get the proper tyre size and give back the ones you are unhappy with because now you know.

[IAmATeaf]

What pressure is the tyre inflated to?

[2000Z3M]

i had 225s up front, went to 245s last week. car drives much better now, less understeer and much more grip. also get the pilot super sport, a true sports tire

[freespirit]

Originally Posted by IAmATeaf

What pressure is the tyre inflated to?

The tire shop had it inflated to 37psi all around , felt wobbling with that psi then i changed it to 34psi and 33psi still the same feeling.

[freespirit]

Originally Posted by 2000Z3M

i had 225s up front, went to 245s last week. car drives much better now, less understeer and much more grip. also get the pilot super sport, a true sports tire

what's the tire inflation you are using ? is it AWD ?

[2000Z3M]

Originally Posted by jkishoret

what's the tire inflation you are using ? is it AWD ?

rwd still working out the ideal psi, been raining a lot here so havent done the chalk test

[BEAR-AvHistory]

Are the tires too wide for the wheels? Ran 245/275 X 19" NRF on a RWD 335is with no handling issues. Current owner Auto-X's the car.

[freespirit]

Originally Posted by BEAR-AvHistory

Are the tires too wide for the wheels? Ran 245/275 X 19" NRF on a RWD 335is with no handling issues. Current owner Auto-X's the car.

doesn't feel too wide ... may be i can post some pics in few hours.

[freespirit]

Originally Posted by 37psi

Yes it can cause wobble and handling problems. Due to the tyres he put on your speedo is out by 1 per cent - not a big deal. However, you have lost more than 3mm on wheel arch gap with a bigger tyre. This in turn impacts on the front geometry. Your options are get the original tyre size intended or get a full geometry done i.e. alignment, camber and, toe adjustment.

It's nothing dangerous it just means your car won't handle as intended and you won't enjoy it. Get the proper tyre size and give back the ones you are unhappy with because now you know.

So the wobbling has nothing to do with non RF...correct ?

[2000Z3M]

Originally Posted by jkishoret

So the wobbling has nothing to do with non RF...correct ?

could be bushing, out of balance tires, anything.

[Soul_Glo]

Originally Posted by jkishoret

So the wobbling has nothing to do with non RF...correct ?

Unlikely to be related to non rf

[BEAR-AvHistory]

Originally Posted by jkishoret

doesn't feel too wide ... may be i can post some pics in few hours.

You misunderstood the question. Its the width of the wheel itself.

The car might have wheels that are too narrow for the tires.

Michelin spec is:

225/45R18 Rim width 7" to 8.5" Sweet spot 7.5"

245/40R18 Rim width 8" to 9.5" Sweet spot 8.5"

I have no idea what your stock wheel size is so you need to look it up.

[eluded]

Originally Posted by BEAR-AvHistory

Michelin spec is:

225/45R18 Rim width 7" to 8.5" Sweet spot 7.5"

245/40R18 Rim width 8" to 9.5" Sweet spot 8.5"

I have no idea what your stock wheel size is so you need to look it up.

This. I think they're 19 x8 on the front.

There is no way I'd run 245 with 255's in the back on this car. That would totally mess up the handling and it would probably make the car a little tail happy.

[2000Z3M]

Originally Posted by eluded

This. I think they're 19 x8 on the front.

There is no way I'd run 245 with 255's in the back on this car. That would totally mess up the handling and it would probably make the car a little tail happy.

op states 18s they should be 8s up front and 8.5s out back. why do you thing that? putting wider tires up front will not make the car tail happy. BMW sets all of their cars up with understeer from the factory.

[BEAR-AvHistory]

Agree, no reason for the handling to go south over the tire size switch. That said if it was good before the tire change & bad after it has to be tire related.

Out of round tire, bad balance, did something get damaged on the lift? etc. Problem is "wobbly" is a non description to try to trouble shoot.

[freespirit]

Originally Posted by BEAR-AvHistory

You misunderstood the question. Its the width of the wheel itself.

The car might have wheels that are too narrow for the tires.

Michelin spec is:

225/45R18 Rim width 7" to 8.5" Sweet spot 7.5"

245/40R18 Rim width 8" to 9.5" Sweet spot 8.5"

I have no idea what your stock wheel size is so you need to look it up.

I think front 8 and rear 8.5

[jjhebigscreen]

I would have the proper size tire put on the fronts and then evaluate how you like the tires. I can tell you I recently put on pirelli p zero all season non rft tires. I drove on them for about two weeks. At first I liked the new tire as impacts over bad pavements where less harsh . As i drove more on themI noticed the steering in the car felt more disconnected and the suspension was bouncier. After two weeks I returned the tires and swapped them for the original pirelli p7 cinturato all season rft. The rft definitely are harsher over broken pavement but I think they handle much better and feel more planted on the highway. I have the base x drive suspension. I am lucky as Discount Tire in my area matches tires racks pricing and lets you return your tires with in the first 30 days and re select if you are not happy. Most posters seem to like the switch to non rft. For me I am way happier with the way the car feels with original rft. Maybe non x drive suspensions would drive and handle better if you switch to non rft tires?

[freespirit]

Originally Posted by jjhebigscreen

I would have the proper size tire put on the fronts and then evaluate how you like the tires. I can tell you I recently put on pirelli p zero all season non rft tires. I drove on them for about two weeks. At first I liked the new tire as impacts over bad pavements where less harsh . As i drove more on themI noticed the steering in the car felt more disconnected and the suspension was bouncier. After two weeks I returned the tires and swapped them for the original pirelli p7 cinturato all season rft. The rft definitely are harsher over broken pavement but I think they handle much better and feel more planted on the highway. I have the base x drive suspension. I am lucky as Discount Tire in my area matches tires racks pricing and lets you return your tires with in the first 30 days and re select if you are not happy. Most posters seem to like the switch to non rft. For me I am way happier with the way the car feels with original rft. Maybe non x drive suspensions would drive and handle better if you switch to non rft tires?

Thats my exact feeling... the driving feels so comfortable with no noise and feels like i am driving on a cloud... but at the same time its not a true BMW ride ... the solid feel on the road is lost ... thinking to go back to RFT ... but which one is the question