Max tire size without changing the stock offset

[kluke15]

i put a 9.5" pp wheel up front with a 285 and personally didnt like it. bulged a bit too much and was real close to strut. went with 275 on my last set and i like it a lot better and a lot less tramlining.

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[NightmareMoon]

Don’t want to change the offset for fear of damage to bearings and what not

The bearings are a wear item, and reasonable changes offset won't be a worry.

Keep in mind Ford uses a bunch of different offsets as well.

 

[Double]

The bearings are a wear item, and reasonable changes offset won't be a worry.

Keep in mind Ford uses a bunch of different offsets as well.

What would be reasonable, anything under 10mm change?

All Ford wheel options I can find are all ET52.5 rear and ET40 front. Which would make sense since anything else will create an uneven load.

 

[kz]

What would be reasonable, anything under 10mm change?

All Ford wheel options I can find are all ET52.5 rear and ET40 front. Which would make sense since anything else will create an uneven load.

Don't want to get too deep in the discussion but offset really doesn't matter much load-wise - load is being transferred primarily at the wheel / hub interface through friction (that lug clamp is there to maintain). You are overthinking this - people are running ET52 wheels in front with 30mm spacers (effectively 22mm offset) with way higher loads than an average Mustang sees. They're fine. Don't worry about loads and focus on what you like.

Edit - also OEM PP2 front wheels are ET24 if I remember correctly - with rest of the parts being identical - this should rest your mind your worries about loads at ease.

 

[Skye]

FWIW, I agree with comments on load: don't be concerned. While you may be interested in vertical or horizontal forces of a wheel change, the rotating mass is going to increase as well. Different mechanical loads or forces will increase in several areas.

IMO, your focus should be on best fitment. The tire and rim diameter/width/offset should work together. Offset is important, but it isn't so critical you have to stay factory; there's no advantage in maintaining the original offset; it should compliment (and most likely change) with the new tire and rim.

https://www.offfset.com/pages/wheel-fitment-calculator

https://tiresize.com/calculator/

If you have time, study changes at various sites which will give you both fitment views and relative percentage changes. IMO, its a good idea to stay within +/- 3% existing diameter, although I know many can and do deviate from this without issue. Some sites can give you fitment views as the offset changes.

Lots of good comments coming in. Let us know later what you pick.

 

[Double]

Cheers, this does help ease some concerns

 

[NightmareMoon]

What would be reasonable, anything under 10mm change?

All Ford wheel options I can find are all ET52.5 rear and ET40 front. Which would make sense since anything else will create an uneven load.

Well the PP2 ran a ET24 front and a ET48 rear.

If offset did accelerate wear (by much), we’d see more hub failures, Nd honestly we don’t see front hub failures hardly at all. Rears, yes sometimes, but not mainly due to offset. They just don’t last forever, and the newer parts seem to last a lot longer than the rear hubs when the S550 first came out.

 

[Double]

Any comments on the added weight on the outside of the wheel when going from 19” to 20”. And its effects on performance? I’m just a weekend cruiser on backroads and the yearly roadtrip. But been reading up on 19” vs 20” and 19” seem to be getting more popular again because of the many added benefits apart from the “looks”. But I can’t really find a 19” combination that won’t increase my wheel gap without lowering the car a ton (we have many speed bumps, there are 5 between me and the highway just 1 mile away)

What i’m looking at now is going from 275/40/19 to 295/35/20. Which would make the whole setup about 1.7% bigger and some added weight. Although I would assume the PP2 19” are pretty heavy compared to aftermarket 20”.

 

[NightmareMoon]

Any comments on the added weight on the outside of the wheel when going from 19” to 20”. And its effects on performance? I’m just a weekend cruiser on backroads and the yearly roadtrip. But been reading up on 19” vs 20” and 19” seem to be getting more popular again because of the many added benefits apart from the “looks”. But I can’t really find a 19” combination that won’t increase my wheel gap without lowering the car a ton (we have many speed bumps, there are 5 between me and the highway just 1 mile away)

What i’m looking at now is going from 275/40/19 to 295/35/20. Which would make the whole setup about 1.7% bigger and some added weight. Although I would assume the PP2 19” are pretty heavy compared to aftermarket 20”.

It depends on the weights of your chosen wheel and tire package. Usually 20 wheels will weight more than 19s, and usually 20" tires will weigh more too. If you get nice forged lightweight wheels and lighter tires, you may come out ahead. The rotating mass being located at a greater radius makes a small difference to acceleration (on paper) but in practice our cars are usually traction limited at the low speeds where it makes the most difference.

Its not a huge factor for handling, but the weight can make it harder to absorb bumps, and that can be a small factor for handing on rough roads.

The stock cast wheels are pretty heavy, so if you get some high quality aftermarket spin forged wheels that does help. Check the construction type and weight on your chosen wheels before buying.

Personally I think 19s are the sweet spot, and with aggressive wheel offsets, the wheel gap isn't an issue. The offset makes the gap visually smaller.

 

[Rick#7]

The factory 19" are pretty heavy, it shouldn't be too hard finding an aftermarket wheel of similar or lighter weight, even in 20" sizes. 295/35/20 will fit up front but it will be tight, offset will be critical, too little and it will poke, too much and it will rub on the strut. 32-34 mm offset should be the sweet spot for a 10-10.5" wide wheel, but confirm that with accurate measurements on your car, production tolerance being what it is can mean slight variations from one car to the other.

Having said that, I have 20" wheels on my car with 275/35 on the front, and if I had to do it all over again I'd stay with 19" and do 275/40 square.

 

[Double]

The factory 19" are pretty heavy, it shouldn't be too hard finding an aftermarket wheel of similar or lighter weight, even in 20" sizes. 295/35/20 will fit up front but it will be tight, offset will be critical, too little and it will poke, too much and it will rub on the strut. 32-34 mm offset should be the sweet spot for a 10-10.5" wide wheel, but confirm that with accurate measurements on your car, production tolerance being what it is can mean slight variations from one car to the other.

Having said that, I have 20" wheels on my car with 275/35 on the front, and if I had to do it all over again I'd stay with 19" and do 275/40 square.

Fronts would be 265/35/20. Why would you go back to 275/40 19” squared over the 20”?

 

[Rick#7]

Because 275/40r19 tires are much cheaper to buy, aftermarket 19" wheels are generally lighter weight than 20" (yes I know there are exceptions), and I happen to think 19" wheels with a taller sidewall looks better on these cars than 20" with a shorter sidewall.

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