Best tire size for 17x8 on e36?

[elton123]

I just bought some 17x8 M5 replicas (man theyre heavy) anyone knowledgeable know what is the best tire size to run in the front and back?

Elton M.

[Infini IV]

Can't go wrong with a 235/40 tire.

[elton123]

is the ride quality worse on /40 than /45 ?

cause discount tires they recommend the /45

[paul e]

is the ride quality worse on /40 than /45 ?

cause discount tires they recommend the /45

Depending on the tire's cross section (which is what the 40 or the 45 represents as a percentage of that cross section which goes into giving you your sidewall height, ie, the amount of 'cushioning' youll get from the tire.. in a very general way of course ;) ), the difference between a 40 and a 45 tire often times on our cars represents around a half inch of sidewall height.. On a 235 tire, for instance, a 40 tire gives you a sidewall height of 3.7" while the 45 tire's sidewall height rounds off to 4.2". Does that half inch of extra sidewall make a difference in ride? I would say that the inflation pressure inside the tire plus the sidewall height are the two factors most responsible for your ride quality, after controlling for suspension of course :D Of course, runflat tires are a whole nother ballgame!

[sirius600]

Depending on the tire's cross section (which is what the 40 or the 45 represents as a percentage of that cross section which goes into giving you your sidewall height, ie, the amount of 'cushioning' youll get from the tire.. in a very general way of course ;) ), the difference between a 40 and a 45 tire often times on our cars represents around a half inch of sidewall height.. On a 235 tire, for instance, a 40 tire gives you a sidewall height of 3.7" while the 45 tire's sidewall height rounds off to 4.2". Does that half inch of extra sidewall make a difference in ride? I would say that the inflation pressure inside the tire plus the sidewall height are the two factors most responsible for your ride quality, after controlling for suspension of course :D Of course, runflat tires are a whole nother ballgame!

But what does it all mean?!?! :banghead:

Many tires i've been looking at (many Kumho's and Toyo's) do not come in 235/40/17s, only 235/45/17. Even the tires that are on here from when i purchased my M3 are 235/45. What would the noticable efects on this be? I'm needing to replace mine soon.

[Estrl M3]

no negative effects just a taller tire.

[Rud]

is the ride quality worse on /40 than /45 ?

cause discount tires they recommend the /45

The 235/40 will be slightly smaller (1.1%) than the stock 205/60, so your speedo will read a teeny bit high.

The 235/45 will be slightly bigger (2.6%) so your speedo will read a teeny bit low.

Acceleration will be a teeny bit better with the 235/40 than with the 235/45.

[sirius600]

http://forums.bimmerforums.com/forum/showthread.php?p=8366786#post8366786

Similar issue, could use some input.

[jvsantosmd]

Don't try anything above 225 front, 235 rear. Anything else will rub inside the fenders at some time. Be sure to get quality rear camber adjustment bars. As brands go, I have had very good experience with Dunlop 9000's (my car has been with me for 200,000 miles). Goodyear F1's are nice looking, very good grip in wet but noisy and short lived. Good luck.
Jose

[Bryce M.]

another thing to look at is the Overall Diameter of the tire...the 225/45 tire has the same OD as the tires from the factory. The e46 cars that came with 17" wheels from the factory had the same 225/45-17 tires. My personal opinion is dont mess with what bmw engineered (that is if you have a stock car). They will give you a great ride as well.