Hello to everybody,

I was wondering if anyone has tried fitting 21" wheels to the rear only?
Can the original front size (255/35 R20) work with a 295/25 R21 rear?

Thanks

 

I have tried quite a few different set ups, you will be fine, the car is not picky*

 

I have 21's all round but recently went to a slightly bigger sidewall on the rear, (305/30/21 instead of 305/25/21) so it was an extra 12mm all round apparently.

I reckon since the new tyres my front has scraped a little more coming out of the driveway. In my imagination, this is because the higher rear tyre has resulted in the front being minutely closer to the ground, it was always very close before but that extra few mm might be making a difference.

 

Thanks for replies, pics for inspiration please!

 

haha, I popped pictures up of mine here a few days ago. I think the pic from the front has the new tyres (30) and the one from the back has the 25's https://www.jaguarforums.com/forum/f...-273258/page2/
here is one of the new tyres

 

Nice!
And front are standard 30?
Is your car lowered?

 

Cheers, the fronts are 265/30/21 from memory. I edited the previous post with a close up of the rears.

The car isnt lowered, I have enough trouble getting over the kerb as it is lol. I think the wider rims fill out the arches so it doesnt need to be lowered, though if you look at this thread (where I pinched the idea and sizes from) he had his lowered, looks pretty flash https://www.jaguarforums.com/forum/f...talled-203620/

 

I like it both

Sorry, just a little OT:

I have noticed that many people have installed a non-genuine wing. Does it slide out with the trunk lid?

 

I haven't heard of anyone using 20" on the front and 21" on the rear, but would be concerned about the rolling radius being different enough that the stability control might get confused. If it interprets the front to rear wheel speeds as different enough it might trigger the traction control. I don't know and have no direct experience, but that's the kind of thing that would concern me. I'm not sure how much variance is allowed, but look at the specs on a site like tirerack and compare revolutions per mile. Hopefully someone will chime in with a maximum percentage that the system will tolerate.

 

Not arguing, just interested - wouldnt it depend on the size of the sidewall on the tyre? Eg 20's with 40 sidewall would be pretty close to 21's with 25, there have defs been no difference to me going from 25 sidewall to 30 on the rears notwithstanding an extra 12mm height all around, meaning that the diameter of the tyre is about an inch bigger. But I honestly have no idea about this stuff, despite my enthusiasm for it.

I did ask the tyre guys in relation to the speedo reading and they said "Essentially you will have about 12mm more meat on the tyre sidewall all around!



TBH I have always assumed that speedo's take revs from front end, as that is where the ABS sensors are.



Looking at this photo you sent a few years back it looks like there is plenty of room as its not lowered or anything, so an educated guess tells me it would work fine, and feel great - and personally something i would probably do. But nope, have not tried and tested yet! You would be the first!"

 

I'm not sure where the speedo gets its information, but all four wheels have speed sensors that are used for more than just ABS, e.g. "torque vectoring by braking." I'm sure there is also a yaw sensor that goes to DSC since my previous car had one. In the Olden Days mechanical speedos usually picked up from a front wheel, like the VW bug or more commonly from the transmission.

Revolutions per mile for a given tire is probably the most reliable measure here. That information is available at places like tirerack.com. I expect there is a range of acceptability for the system, but don't know what would happen if you went outside that. Again, this is all academic to me, but as a tech nerd I do find it interesting.

 

Well, that's exactly what I'm afraid of, that's why I asked. When I had an AWD BMW E92, the diameter difference had to be within 1%. The question is how here in the case of RWD.

 

I doubt that this helps, but my rears appear to be 20mm larger in diameter than the fronts (which over the total of 700mm is about 3% bigger) and I have lived to tell the tale about 1500km later.

 

In this conversation, just to set the record straight: There are 3.2 mm to 1/8 inch; therefore, 12mm is 15/32 (roughly 1/2") and 20mm is 25/32 (roughly 3/4+") of increased diameter. Please continue.

 

My apologies, to put it into perspective for my non Australian friends, the rear wheels are about the diameter of 3 remington 7mm magnum shells bigger than the fronts which are a male (2 year old bald eagle) long (which is about the same as 4.5 Glock 43's end on end)

 

Stick pirelli 255 35 20 / 295 30 20

Pirelli winter Sotto zero 255 35 20 / 295 30 20

Pirelli winter sotto zero 255 35 20 / 295 30 20

R888r 255 35 20 / 305 35 20(rubbing with lower offset wheel until fender were trimmed), lowered on vap springs





Goodyear supercar3 245 35 20 / 285 30 20 on 9.5 and 11” rims and lowered on h&r, Went too conservative on the rear, should have gone with 35 profile and it will be perfect. New rear shock and worn front component isn’t helping either, i will get a side profile later, the rear is sitting too high.


large rear wheel(by higher profile tire or 21” rims) lowered is by far my favorite stance, rwd will be 100% fine and no adverse effect as far as i can tell, you will feel the difference in tire much much more than the minuscule change in overall diameter

 

Now I have the same OEM wheels But black.