znalazłem ciekawy post w zagranicznym forum mazdy, mniej wiecej sobie go przetlumaczyłem i wychodzi z tego postu ze bez rolowania wchodza fele 18x8 i et 45 z opona 225/40r18 do mojej Madzi, i nic nie obciera

chyba ze jest opona 235/40r18 wtedy jest problem

Fajnie by było gdyby ktoś to potwierdził.
Originally Posted by Cali_Axela
Your Mazda3 or Mazdaspeed3 (and any other late model Mazda, in fact) requires wheels with these basic specs:
– 5x114.3 bolt patten
– 67.1mm hub bore*
* larger hub bore wheels can also be used (e.g. 73mm, a very common hub bore), however hubcentric centering rings are recommended for fitting wheels with a larger hub bore to ensure correct centering.
– Wheel diameter between 16" and 20"*
* the 2.0L i Mazda3 can also fit 15" wheels, but 2.3L or Mazdaspeed3 models cannot. 16" wheels are fine on any normal 3, but a very tight fit over the MS3 front brakes, so it's possible not ALL 16" wheels will work on an MS3. Wheel diameters larger than 20" may be possible, but the paper-thin tire sizes required for proper fitment would make the car very impractical and uncomfortable to drive and it's not recommended at all.
The other two factors in wheel fitment are width and offset. OEM 17" wheels have an offset of 52.5mm and width of 6.5". In general, the wider you go, the lower the offset needs to be in order to clear the suspension components. These two factors, width and offset, are the most variable components of wheel fitment, compared to all the other variables which are pretty much set in stone. Thus, they are the most important to look at closely.
"Safe" upgraded fitment -- these will work with any model, retain the correct speedometer readings etc just like OEM, and work in all conditions with any off-the-shelf suspension height and settings without any fender modification required.
17x7" wheels with an offset between +45 to +54
17x7.5" wheels with an offset between +47 to +50
The recommended tire size for these 17" common upgrades on a Mazda3 is 225/45/17. The recommended tire size for these 17" common upgrades on a Mazdaspeed3 is 235/45/17.
18x7" wheels with an offset between +45 to +54
18x7.5" wheels with an offset between +47 to +52
The recommended tire size for these 18" common upgrades on a Mazda3 is 225/40/18. The recommended tire size for these 18" common upgrades on a Mazdaspeed3 is 235/40/18. The 7.5" is strongly recommended over the 7" for an MS3.
Moderately aggressive fitment -- these are fitments that push the OEM fender envelope, so to speak. Depending on what suspension you're running and how much weight is in your car, you may or may not need to roll your rear fenders to make these work without rubbing. Higher offsets are more likely to work without a roll (e.g. 17x8 +50 will work without a roll on most cars, while 17x8 +40 will require a roll on most cars... but how much they rub depends largely on your suspension setup).
17x8" wheels with an offset between +40 to +50
17x8.5" wheels with an offset between +42 to +48
The recommended tire size for these 17" common upgrades on a Mazda3 is 225/45/17. The recommended tire size for these 17" common upgrades on a Mazdaspeed3 is 235/45/17.
18x8" wheels with an offset between +40 to +50
18x8.5" wheels with an offset between +42 to +48
The recommended tire size for these 18" common upgrades on a Mazda3 is 225/40/18. The recommended tire size for these 18" common upgrades on a Mazdaspeed3 is 235/40/18. The 8.5" is recommended over the 8" for an MS3; you could alternately stretch some 235/40/18 tires (the MS3 tire recommendation for narrower wheels) onto these wider wheels.
Extra aggressive fitment
Wider wheels (9" – 10" can also be fitted, with an offset in the +30 to +45 range, however a very good fender roll, exact measurements or trail-and-error, and even a minor pull will be required. Significant additional negative camber over OEM recommendations will also likely be required in order to avoid the wheels "poking" out of the fenders. Basically, be prepared to do work, not just bolt them on.