kos11-12

I guys ,

I am getting confused, 235/40 front on 8 x 18 and 265/35 rear on 9 x 10, is that ok ?

on toyos R888 web site they say it's ok, thanks your comments,

Konstantin C4 92

Bill Verburg

It would help if you specified a tire, becasue they are sometimes different wrt wheel widths but in general
235/40 x18 wants a 8-9.5" wide bead and 265/35 x18 wants a 9 - 10.5" bead.

So yes, for most tires that is going to be acceptable

kos11-12

Hello Bill,

thanks for your reply, it will be with TOYOs R888, do you think i would still be able to use of all the tread width

Bill Verburg

well it's acceptable, barely, but the issue is that they really do want a wider bead to fully support the tread, if money were no object, and you wanted to optimize performance you would want 9.5" & 10.5" beads if they would fit. Since we all compromise you either use them or go to smaller tires 225/40 & 255/35 x18. I suspect that you would like the smaller tires as well or better, given that they are shorter and may(usually will) help gearing a tad and they will be a little lighter and the sidewalls will be better supported, all little things but many little things can add up.

kos11-12

this is what I though, I am trying to chose a size for new rims, with the right ET, I think I will go for
8 1/2 and 10

thanks Bill

Bill Verburg

8ET50 & 10ET65( w ~ 18mm spacers) certainly fit
this one has 8 & 10 x18, 245/35 and 275/35 x18 and it was performing admireably

kos11-12

very nice car, so what is the benefit of using a 245 on a 8 and a 275 on a 10 for this car ?

Bill Verburg

it's a race car, the tires are relatively short for their width and that was the compromise selected keeping in mind that a lower profile tire will generally perform better than a higher profile one. For comfort the opposite is true

in front w/ Hoosiers on an 8x18 wheel the choices are
225/40 which is roughly 9.3x24.8 & w/ 8.8" of tread - the usual for this wheel
245/35 which is roughly 9.6x24.7 & w/ 9.1" of tread - actually fits better because it's shorter and gives more tread, it would be better on a wider wheel but that would be harder to fit
245/40 which is roughly 10.25x25.7 & w/ 9.3" of tread - too tall

in back on a 10x18 wheel
255/40 which is roughly 11.1x26.2 & w/ 9.8" of tread - the smallest tire that fits on a 10
275/35 which is roughly 11.1x25.5 & w/ 10.3" of tread - compromise
285/30 which is roughly 11.5x24.9 & w/ 10.9" of tread - this would have been my first choice but it may have been too wide to fit in the wheel well again it would be a better performer on a 10.5 or 11" wheel

other tire manufacturers would have different offerings, you'll have to pick and choose

kos11-12

ok ! understand thanks for the explanation Bill

all the best

Konstantin

Henrik964

Just curious, could You fit a 235/40/18 on an 10" rim?

Porsche964FP

Hi Bill, thanks for the insight. You've given me food for thought.

For the sake of asking an obvious question, am I right in understanding that 245/ 35 will obviously be wider and have a shorter profile than 225/ 40?

I'll be putting on new tyres on my 8 & 9.5 18" rims. Currently I'm being advised 225/ 40 and 265/35.... I'd like something a with a shorter profile and a little wider... What are your recommended options?

I appreciate you've addressed 8X18 but how about 9.5x18?

Cheers,

Bill Verburg

It depends on the tires sizes that are available for the specific tire you want to use, on my blue car w/ 8.5 & 10 I use MPSC, front could be 235/40 or 225/40, rear couls be 285/30 or 265/35. I use 225/265 because I don't like the height of the 235/40 and I particularly don't like the height difference between 235 & 285(it is theoretically acceptable for ABS, but can't help)

If I switched to Hosiers I'd use 245/35 & 280/30 as the wider lower tires w/ the same heights would work great.

For a 964 w/ 8 & 9.5 the same sort of analysis would hold, If you use MPSC 225/40 & 265/35, if you use Toyo RA1 245/40 and 275/35 while not ideal and sort of tall are the only choice. So look at what's available and make the best compromise the fits

Porsche964FP

Thanks Bill.
So with the tyres I'm looking at I've got several options. 225/40 front 265/35 rear and 225/35 front 265/30 rear.

I like the sound of lower profile, less wobble, however this would lower the car further and increase the distance between the tops of the wheel arches and the tops of the tyres, no?

Bill Verburg

For most of us 225/40 & 265/35 are going to be fine and all the tiore we could ever use

I'm curious as to who makes a 225/35x18

Earlydays

Bridgestone/Continental/Goodyear/BFG....